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[Linux-stable-mirror] [PATCH 4.4] fscrypt: lock mutex before checking for bounce page pool

by Eric Biggers

commit a0b3bc855374c50b5ea85273553485af48caf2f7 upstream. [Please apply to 4.4-stable.] fscrypt_initialize(), which allocates the global bounce page pool when an encrypted file is first accessed, uses "double-checked locking" to try to avoid locking fscrypt_init_mutex. However, it doesn't use any memory barriers, so it's theoretically possible for a thread to observe a bounce page pool which has not been fully initialized. This is a classic bug with "double-checked locking". While "only a theoretical issue" in the latest kernel, in pre-4.8 kernels the pointer that was checked was not even the last to be initialized, so it was easily possible for a crash (NULL pointer dereference) to happen. This was changed only incidentally by the large refactor to use fs/crypto/. Solve both problems in a trivial way that can easily be backported: just always take the mutex. It's theoretically less efficient, but it shouldn't be noticeable in practice as the mutex is only acquired very briefly once per encrypted file. Later I'd like to make this use a helper macro like DO_ONCE(). However, DO_ONCE() runs in atomic context, so we'd need to add a new macro that allows blocking. Cc: stable(a)vger.kernel.org # v4.1+ Signed-off-by: Eric Biggers <ebiggers(a)google.com> Signed-off-by: Theodore Ts'o <tytso(a)mit.edu> --- fs/ext4/crypto_key.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/fs/ext4/crypto_key.c b/fs/ext4/crypto_key.c index 9a1bc638abce..9308fe4b66e6 100644 --- a/fs/ext4/crypto_key.c +++ b/fs/ext4/crypto_key.c @@ -129,11 +129,9 @@ int ext4_get_encryption_info(struct inode *inode) if (ei->i_crypt_info) return 0; - if (!ext4_read_workqueue) { - res = ext4_init_crypto(); - if (res) - return res; - } + res = ext4_init_crypto(); + if (res) + return res; res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION, EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, -- 2.15.0.417.g466bffb3ac-goog

7 years, 7 months

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[Linux-stable-mirror] [PATCH 4.9] fscrypt: lock mutex before checking for bounce page pool

by Eric Biggers

commit a0b3bc855374c50b5ea85273553485af48caf2f7 upstream. [Please apply to 4.9-stable.] fscrypt_initialize(), which allocates the global bounce page pool when an encrypted file is first accessed, uses "double-checked locking" to try to avoid locking fscrypt_init_mutex. However, it doesn't use any memory barriers, so it's theoretically possible for a thread to observe a bounce page pool which has not been fully initialized. This is a classic bug with "double-checked locking". While "only a theoretical issue" in the latest kernel, in pre-4.8 kernels the pointer that was checked was not even the last to be initialized, so it was easily possible for a crash (NULL pointer dereference) to happen. This was changed only incidentally by the large refactor to use fs/crypto/. Solve both problems in a trivial way that can easily be backported: just always take the mutex. It's theoretically less efficient, but it shouldn't be noticeable in practice as the mutex is only acquired very briefly once per encrypted file. Later I'd like to make this use a helper macro like DO_ONCE(). However, DO_ONCE() runs in atomic context, so we'd need to add a new macro that allows blocking. Cc: stable(a)vger.kernel.org # v4.1+ Signed-off-by: Eric Biggers <ebiggers(a)google.com> Signed-off-by: Theodore Ts'o <tytso(a)mit.edu> --- fs/crypto/crypto.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 61cfccea77bc..73de1446c8d4 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -484,9 +484,6 @@ int fscrypt_initialize(void) { int i, res = -ENOMEM; - if (fscrypt_bounce_page_pool) - return 0; - mutex_lock(&fscrypt_init_mutex); if (fscrypt_bounce_page_pool) goto already_initialized; -- 2.15.0.417.g466bffb3ac-goog

7 years, 7 months

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Re: [Linux-stable-mirror] [PATCH] Ensure that the SCSI error handler gets woken up

by Pavel Tikhomirov

1-st, Stuart - thanks for adding me to CC, 2-nd Bart - no idea why you didn't? =) > If scsi_eh_scmd_add() is called concurrently with scsi_host_queue_ready() > while shost->host_blocked > 0 then it can happen that neither function > wakes up the SCSI error handler. Fix this by making every function that > decreases the host_busy counter to wake up the error handler if necessary. Bart, you've added a comment to my initial patch() about performance, let me quote it here: > An important achievement of the scsi-mq code was removal of all > spin_lock_irq(shost->host_lock) statements from the hot path. The above > changes will have a significant negative performance impact, especially if > multiple LUNs associated with the same SCSI host are involved. Can the > reported race be fixed without slowing down the hot path significantly? I > think that both adding spin lock or smp_mb() calls in the hot path will > have a significant negative performance impact. These was a tricky question so I had no immediate answer. Here is the one: a) We need to check if scsi_eh_wakeup needs to wake up error handler thread in every place where we change host_busy. Else we have a chance that these change will break the wake up check in other existing places and will lead to deadlock. b) If we have several variables and change them (one different variable in in different thread) and after that we want to check the joint state of these variables, we sould surely have some kind of memory barriers to have a consistent state at some point. c) We already have spinlocks in scsi_schedule_eh, scsi_eh_scmd_add and scsi_device_unbusy, so it seems the good thing to reuse them for new checks too. I don't see another way to fix these problem. Your patch puts spinlocks under check which should itself be under spinlock, and breaks the initial fix (see Stuart's comment that the problem still reproduces). And you does _not_ answer your own question. > > Reported-by: Pavel Tikhomirov <ptikhomirov@xxxxxxxxxxxxx> > Fixes: commit 746650160866 ("scsi: convert host_busy to atomic_t") > Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx> As your patch is based on my initial patch (https://patchwork.kernel.org/patch/9938919/), when all problems will be resolved with it, can you please add here: Signed-off-by: Pavel Tikhomirov <ptikhomirov(a)virtuozzo.com> > Cc: Konstantin Khorenko <khorenko@xxxxxxxxxxxxx> > Cc: Stuart Hayes <stuart.w.hayes@xxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Hannes Reinecke <hare@xxxxxxxx> > Cc: Johannes Thumshirn <jthumshirn@xxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> > --- > drivers/scsi/scsi_error.c | 3 ++- > drivers/scsi/scsi_lib.c | 22 ++++++++++++++-------- > 2 files changed, 16 insertions(+), 9 deletions(-) > > diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c > index 5e89049e9b4e..f7f014c755d7 100644 > --- a/drivers/scsi/scsi_error.c > +++ b/drivers/scsi/scsi_error.c > @@ -61,9 +61,10 @@ static int scsi_eh_try_stu(struct scsi_cmnd *scmd); > static int scsi_try_to_abort_cmd(struct scsi_host_template *, > struct scsi_cmnd *); > > -/* called with shost->host_lock held */ > void scsi_eh_wakeup(struct Scsi_Host *shost) > { > + lockdep_assert_held(shost->host_lock); > + > if (atomic_read(&shost->host_busy) == shost->host_failed) { > trace_scsi_eh_wakeup(shost); > wake_up_process(shost->ehandler); I also think these hunk is just an additional precaution and should be in separate patch. > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 1e05e1885ac8..abd37d77af2d 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -318,22 +318,28 @@ static void scsi_init_cmd_errh(struct scsi_cmnd *cmd) > cmd->cmd_len = scsi_command_size(cmd->cmnd); > } > > -void scsi_device_unbusy(struct scsi_device *sdev) > +static void scsi_dec_host_busy(struct Scsi_Host *shost) > { > - struct Scsi_Host *shost = sdev->host; > - struct scsi_target *starget = scsi_target(sdev); > unsigned long flags; > > atomic_dec(&shost->host_busy); > - if (starget->can_queue > 0) > - atomic_dec(&starget->target_busy); > - > if (unlikely(scsi_host_in_recovery(shost) && > (shost->host_failed || shost->host_eh_scheduled))) { As I've wrote above you do wrong locking here in scsi_dec_host_busy. Note that the above check reads host_failed and can load host_failed before host_busy is decremented due to reordering. > spin_lock_irqsave(shost->host_lock, flags); > scsi_eh_wakeup(shost); > spin_unlock_irqrestore(shost->host_lock, flags); > } > +} > + > +void scsi_device_unbusy(struct scsi_device *sdev) > +{ > + struct Scsi_Host *shost = sdev->host; > + struct scsi_target *starget = scsi_target(sdev); > + > + scsi_dec_host_busy(shost); > + > + if (starget->can_queue > 0) > + atomic_dec(&starget->target_busy); > > atomic_dec(&sdev->device_busy); > } > @@ -1532,7 +1538,7 @@ static inline int scsi_host_queue_ready(struct request_queue *q, > list_add_tail(&sdev->starved_entry, &shost->starved_list); > spin_unlock_irq(shost->host_lock); > out_dec: > - atomic_dec(&shost->host_busy); > + scsi_dec_host_busy(shost); > return 0; > } > > @@ -2020,7 +2026,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, > return BLK_STS_OK; > > out_dec_host_busy: > - atomic_dec(&shost->host_busy); > + scsi_dec_host_busy(shost); > out_dec_target_busy: > if (scsi_target(sdev)->can_queue > 0) > atomic_dec(&scsi_target(sdev)->target_busy); > -- > 2.15.0 -- Best regards, Tikhomirov Pavel Software Developer, Virtuozzo.

7 years, 7 months

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[Linux-stable-mirror] Patch "sched/rt: Simplify the IPI based RT balancing logic" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled sched/rt: Simplify the IPI based RT balancing logic to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: sched-rt-simplify-the-ipi-based-rt-balancing-logic.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 4bdced5c9a2922521e325896a7bbbf0132c94e56 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" <rostedt(a)goodmis.org> Date: Fri, 6 Oct 2017 14:05:04 -0400 Subject: sched/rt: Simplify the IPI based RT balancing logic From: Steven Rostedt (Red Hat) <rostedt(a)goodmis.org> commit 4bdced5c9a2922521e325896a7bbbf0132c94e56 upstream. When a CPU lowers its priority (schedules out a high priority task for a lower priority one), a check is made to see if any other CPU has overloaded RT tasks (more than one). It checks the rto_mask to determine this and if so it will request to pull one of those tasks to itself if the non running RT task is of higher priority than the new priority of the next task to run on the current CPU. When we deal with large number of CPUs, the original pull logic suffered from large lock contention on a single CPU run queue, which caused a huge latency across all CPUs. This was caused by only having one CPU having overloaded RT tasks and a bunch of other CPUs lowering their priority. To solve this issue, commit: b6366f048e0c ("sched/rt: Use IPI to trigger RT task push migration instead of pulling") changed the way to request a pull. Instead of grabbing the lock of the overloaded CPU's runqueue, it simply sent an IPI to that CPU to do the work. Although the IPI logic worked very well in removing the large latency build up, it still could suffer from a large number of IPIs being sent to a single CPU. On a 80 CPU box, I measured over 200us of processing IPIs. Worse yet, when I tested this on a 120 CPU box, with a stress test that had lots of RT tasks scheduling on all CPUs, it actually triggered the hard lockup detector! One CPU had so many IPIs sent to it, and due to the restart mechanism that is triggered when the source run queue has a priority status change, the CPU spent minutes! processing the IPIs. Thinking about this further, I realized there's no reason for each run queue to send its own IPI. As all CPUs with overloaded tasks must be scanned regardless if there's one or many CPUs lowering their priority, because there's no current way to find the CPU with the highest priority task that can schedule to one of these CPUs, there really only needs to be one IPI being sent around at a time. This greatly simplifies the code! The new approach is to have each root domain have its own irq work, as the rto_mask is per root domain. The root domain has the following fields attached to it: rto_push_work - the irq work to process each CPU set in rto_mask rto_lock - the lock to protect some of the other rto fields rto_loop_start - an atomic that keeps contention down on rto_lock the first CPU scheduling in a lower priority task is the one to kick off the process. rto_loop_next - an atomic that gets incremented for each CPU that schedules in a lower priority task. rto_loop - a variable protected by rto_lock that is used to compare against rto_loop_next rto_cpu - The cpu to send the next IPI to, also protected by the rto_lock. When a CPU schedules in a lower priority task and wants to make sure overloaded CPUs know about it. It increments the rto_loop_next. Then it atomically sets rto_loop_start with a cmpxchg. If the old value is not "0", then it is done, as another CPU is kicking off the IPI loop. If the old value is "0", then it will take the rto_lock to synchronize with a possible IPI being sent around to the overloaded CPUs. If rto_cpu is greater than or equal to nr_cpu_ids, then there's either no IPI being sent around, or one is about to finish. Then rto_cpu is set to the first CPU in rto_mask and an IPI is sent to that CPU. If there's no CPUs set in rto_mask, then there's nothing to be done. When the CPU receives the IPI, it will first try to push any RT tasks that is queued on the CPU but can't run because a higher priority RT task is currently running on that CPU. Then it takes the rto_lock and looks for the next CPU in the rto_mask. If it finds one, it simply sends an IPI to that CPU and the process continues. If there's no more CPUs in the rto_mask, then rto_loop is compared with rto_loop_next. If they match, everything is done and the process is over. If they do not match, then a CPU scheduled in a lower priority task as the IPI was being passed around, and the process needs to start again. The first CPU in rto_mask is sent the IPI. This change removes this duplication of work in the IPI logic, and greatly lowers the latency caused by the IPIs. This removed the lockup happening on the 120 CPU machine. It also simplifies the code tremendously. What else could anyone ask for? Thanks to Peter Zijlstra for simplifying the rto_loop_start atomic logic and supplying me with the rto_start_trylock() and rto_start_unlock() helper functions. Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Cc: Clark Williams <williams(a)redhat.com> Cc: Daniel Bristot de Oliveira <bristot(a)redhat.com> Cc: John Kacur <jkacur(a)redhat.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Mike Galbraith <efault(a)gmx.de> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Scott Wood <swood(a)redhat.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Link: http://lkml.kernel.org/r/20170424114732.1aac6dc4@gandalf.local.home Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- kernel/sched/core.c | 6 + kernel/sched/rt.c | 235 ++++++++++++++++++++++++--------------------------- kernel/sched/sched.h | 24 +++-- 3 files changed, 138 insertions(+), 127 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5877,6 +5877,12 @@ static int init_rootdomain(struct root_d if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) goto free_dlo_mask; +#ifdef HAVE_RT_PUSH_IPI + rd->rto_cpu = -1; + raw_spin_lock_init(&rd->rto_lock); + init_irq_work(&rd->rto_push_work, rto_push_irq_work_func); +#endif + init_dl_bw(&rd->dl_bw); if (cpudl_init(&rd->cpudl) != 0) goto free_dlo_mask; --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -72,10 +72,6 @@ static void start_rt_bandwidth(struct rt raw_spin_unlock(&rt_b->rt_runtime_lock); } -#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI) -static void push_irq_work_func(struct irq_work *work); -#endif - void init_rt_rq(struct rt_rq *rt_rq) { struct rt_prio_array *array; @@ -95,13 +91,6 @@ void init_rt_rq(struct rt_rq *rt_rq) rt_rq->rt_nr_migratory = 0; rt_rq->overloaded = 0; plist_head_init(&rt_rq->pushable_tasks); - -#ifdef HAVE_RT_PUSH_IPI - rt_rq->push_flags = 0; - rt_rq->push_cpu = nr_cpu_ids; - raw_spin_lock_init(&rt_rq->push_lock); - init_irq_work(&rt_rq->push_work, push_irq_work_func); -#endif #endif /* CONFIG_SMP */ /* We start is dequeued state, because no RT tasks are queued */ rt_rq->rt_queued = 0; @@ -1864,160 +1853,166 @@ static void push_rt_tasks(struct rq *rq) } #ifdef HAVE_RT_PUSH_IPI + /* - * The search for the next cpu always starts at rq->cpu and ends - * when we reach rq->cpu again. It will never return rq->cpu. - * This returns the next cpu to check, or nr_cpu_ids if the loop - * is complete. + * When a high priority task schedules out from a CPU and a lower priority + * task is scheduled in, a check is made to see if there's any RT tasks + * on other CPUs that are waiting to run because a higher priority RT task + * is currently running on its CPU. In this case, the CPU with multiple RT + * tasks queued on it (overloaded) needs to be notified that a CPU has opened + * up that may be able to run one of its non-running queued RT tasks. + * + * All CPUs with overloaded RT tasks need to be notified as there is currently + * no way to know which of these CPUs have the highest priority task waiting + * to run. Instead of trying to take a spinlock on each of these CPUs, + * which has shown to cause large latency when done on machines with many + * CPUs, sending an IPI to the CPUs to have them push off the overloaded + * RT tasks waiting to run. + * + * Just sending an IPI to each of the CPUs is also an issue, as on large + * count CPU machines, this can cause an IPI storm on a CPU, especially + * if its the only CPU with multiple RT tasks queued, and a large number + * of CPUs scheduling a lower priority task at the same time. + * + * Each root domain has its own irq work function that can iterate over + * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT + * tassk must be checked if there's one or many CPUs that are lowering + * their priority, there's a single irq work iterator that will try to + * push off RT tasks that are waiting to run. + * + * When a CPU schedules a lower priority task, it will kick off the + * irq work iterator that will jump to each CPU with overloaded RT tasks. + * As it only takes the first CPU that schedules a lower priority task + * to start the process, the rto_start variable is incremented and if + * the atomic result is one, then that CPU will try to take the rto_lock. + * This prevents high contention on the lock as the process handles all + * CPUs scheduling lower priority tasks. + * + * All CPUs that are scheduling a lower priority task will increment the + * rt_loop_next variable. This will make sure that the irq work iterator + * checks all RT overloaded CPUs whenever a CPU schedules a new lower + * priority task, even if the iterator is in the middle of a scan. Incrementing + * the rt_loop_next will cause the iterator to perform another scan. * - * rq->rt.push_cpu holds the last cpu returned by this function, - * or if this is the first instance, it must hold rq->cpu. */ static int rto_next_cpu(struct rq *rq) { - int prev_cpu = rq->rt.push_cpu; + struct root_domain *rd = rq->rd; + int next; int cpu; - cpu = cpumask_next(prev_cpu, rq->rd->rto_mask); - /* - * If the previous cpu is less than the rq's CPU, then it already - * passed the end of the mask, and has started from the beginning. - * We end if the next CPU is greater or equal to rq's CPU. + * When starting the IPI RT pushing, the rto_cpu is set to -1, + * rt_next_cpu() will simply return the first CPU found in + * the rto_mask. + * + * If rto_next_cpu() is called with rto_cpu is a valid cpu, it + * will return the next CPU found in the rto_mask. + * + * If there are no more CPUs left in the rto_mask, then a check is made + * against rto_loop and rto_loop_next. rto_loop is only updated with + * the rto_lock held, but any CPU may increment the rto_loop_next + * without any locking. */ - if (prev_cpu < rq->cpu) { - if (cpu >= rq->cpu) - return nr_cpu_ids; + for (;;) { - } else if (cpu >= nr_cpu_ids) { - /* - * We passed the end of the mask, start at the beginning. - * If the result is greater or equal to the rq's CPU, then - * the loop is finished. - */ - cpu = cpumask_first(rq->rd->rto_mask); - if (cpu >= rq->cpu) - return nr_cpu_ids; - } - rq->rt.push_cpu = cpu; + /* When rto_cpu is -1 this acts like cpumask_first() */ + cpu = cpumask_next(rd->rto_cpu, rd->rto_mask); - /* Return cpu to let the caller know if the loop is finished or not */ - return cpu; -} + rd->rto_cpu = cpu; -static int find_next_push_cpu(struct rq *rq) -{ - struct rq *next_rq; - int cpu; + if (cpu < nr_cpu_ids) + return cpu; - while (1) { - cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - break; - next_rq = cpu_rq(cpu); + rd->rto_cpu = -1; + + /* + * ACQUIRE ensures we see the @rto_mask changes + * made prior to the @next value observed. + * + * Matches WMB in rt_set_overload(). + */ + next = atomic_read_acquire(&rd->rto_loop_next); - /* Make sure the next rq can push to this rq */ - if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr) + if (rd->rto_loop == next) break; + + rd->rto_loop = next; } - return cpu; + return -1; } -#define RT_PUSH_IPI_EXECUTING 1 -#define RT_PUSH_IPI_RESTART 2 +static inline bool rto_start_trylock(atomic_t *v) +{ + return !atomic_cmpxchg_acquire(v, 0, 1); +} -static void tell_cpu_to_push(struct rq *rq) +static inline void rto_start_unlock(atomic_t *v) { - int cpu; + atomic_set_release(v, 0); +} - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - raw_spin_lock(&rq->rt.push_lock); - /* Make sure it's still executing */ - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - /* - * Tell the IPI to restart the loop as things have - * changed since it started. - */ - rq->rt.push_flags |= RT_PUSH_IPI_RESTART; - raw_spin_unlock(&rq->rt.push_lock); - return; - } - raw_spin_unlock(&rq->rt.push_lock); - } +static void tell_cpu_to_push(struct rq *rq) +{ + int cpu = -1; - /* When here, there's no IPI going around */ + /* Keep the loop going if the IPI is currently active */ + atomic_inc(&rq->rd->rto_loop_next); - rq->rt.push_cpu = rq->cpu; - cpu = find_next_push_cpu(rq); - if (cpu >= nr_cpu_ids) + /* Only one CPU can initiate a loop at a time */ + if (!rto_start_trylock(&rq->rd->rto_loop_start)) return; - rq->rt.push_flags = RT_PUSH_IPI_EXECUTING; + raw_spin_lock(&rq->rd->rto_lock); + + /* + * The rto_cpu is updated under the lock, if it has a valid cpu + * then the IPI is still running and will continue due to the + * update to loop_next, and nothing needs to be done here. + * Otherwise it is finishing up and an ipi needs to be sent. + */ + if (rq->rd->rto_cpu < 0) + cpu = rto_next_cpu(rq); + + raw_spin_unlock(&rq->rd->rto_lock); - irq_work_queue_on(&rq->rt.push_work, cpu); + rto_start_unlock(&rq->rd->rto_loop_start); + + if (cpu >= 0) + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } /* Called from hardirq context */ -static void try_to_push_tasks(void *arg) +void rto_push_irq_work_func(struct irq_work *work) { - struct rt_rq *rt_rq = arg; - struct rq *rq, *src_rq; - int this_cpu; + struct rq *rq; int cpu; - this_cpu = rt_rq->push_cpu; + rq = this_rq(); - /* Paranoid check */ - BUG_ON(this_cpu != smp_processor_id()); - - rq = cpu_rq(this_cpu); - src_rq = rq_of_rt_rq(rt_rq); - -again: + /* + * We do not need to grab the lock to check for has_pushable_tasks. + * When it gets updated, a check is made if a push is possible. + */ if (has_pushable_tasks(rq)) { raw_spin_lock(&rq->lock); - push_rt_task(rq); + push_rt_tasks(rq); raw_spin_unlock(&rq->lock); } - /* Pass the IPI to the next rt overloaded queue */ - raw_spin_lock(&rt_rq->push_lock); - /* - * If the source queue changed since the IPI went out, - * we need to restart the search from that CPU again. - */ - if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) { - rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART; - rt_rq->push_cpu = src_rq->cpu; - } + raw_spin_lock(&rq->rd->rto_lock); - cpu = find_next_push_cpu(src_rq); + /* Pass the IPI to the next rt overloaded queue */ + cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING; - raw_spin_unlock(&rt_rq->push_lock); + raw_spin_unlock(&rq->rd->rto_lock); - if (cpu >= nr_cpu_ids) + if (cpu < 0) return; - /* - * It is possible that a restart caused this CPU to be - * chosen again. Don't bother with an IPI, just see if we - * have more to push. - */ - if (unlikely(cpu == rq->cpu)) - goto again; - /* Try the next RT overloaded CPU */ - irq_work_queue_on(&rt_rq->push_work, cpu); -} - -static void push_irq_work_func(struct irq_work *work) -{ - struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work); - - try_to_push_tasks(rt_rq); + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } #endif /* HAVE_RT_PUSH_IPI */ --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -463,7 +463,7 @@ static inline int rt_bandwidth_enabled(v } /* RT IPI pull logic requires IRQ_WORK */ -#ifdef CONFIG_IRQ_WORK +#if defined(CONFIG_IRQ_WORK) && defined(CONFIG_SMP) # define HAVE_RT_PUSH_IPI #endif @@ -485,12 +485,6 @@ struct rt_rq { unsigned long rt_nr_total; int overloaded; struct plist_head pushable_tasks; -#ifdef HAVE_RT_PUSH_IPI - int push_flags; - int push_cpu; - struct irq_work push_work; - raw_spinlock_t push_lock; -#endif #endif /* CONFIG_SMP */ int rt_queued; @@ -572,6 +566,19 @@ struct root_domain { struct dl_bw dl_bw; struct cpudl cpudl; +#ifdef HAVE_RT_PUSH_IPI + /* + * For IPI pull requests, loop across the rto_mask. + */ + struct irq_work rto_push_work; + raw_spinlock_t rto_lock; + /* These are only updated and read within rto_lock */ + int rto_loop; + int rto_cpu; + /* These atomics are updated outside of a lock */ + atomic_t rto_loop_next; + atomic_t rto_loop_start; +#endif /* * The "RT overload" flag: it gets set if a CPU has more than * one runnable RT task. @@ -584,6 +591,9 @@ struct root_domain { extern struct root_domain def_root_domain; +#ifdef HAVE_RT_PUSH_IPI +extern void rto_push_irq_work_func(struct irq_work *work); +#endif #endif /* CONFIG_SMP */ /* Patches currently in stable-queue which might be from rostedt(a)goodmis.org are queue-4.9/sched-make-resched_cpu-unconditional.patch queue-4.9/sched-rt-simplify-the-ipi-based-rt-balancing-logic.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "sched/rt: Simplify the IPI based RT balancing logic" has been added to the 4.4-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled sched/rt: Simplify the IPI based RT balancing logic to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: sched-rt-simplify-the-ipi-based-rt-balancing-logic.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 4bdced5c9a2922521e325896a7bbbf0132c94e56 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" <rostedt(a)goodmis.org> Date: Fri, 6 Oct 2017 14:05:04 -0400 Subject: sched/rt: Simplify the IPI based RT balancing logic From: Steven Rostedt (Red Hat) <rostedt(a)goodmis.org> commit 4bdced5c9a2922521e325896a7bbbf0132c94e56 upstream. When a CPU lowers its priority (schedules out a high priority task for a lower priority one), a check is made to see if any other CPU has overloaded RT tasks (more than one). It checks the rto_mask to determine this and if so it will request to pull one of those tasks to itself if the non running RT task is of higher priority than the new priority of the next task to run on the current CPU. When we deal with large number of CPUs, the original pull logic suffered from large lock contention on a single CPU run queue, which caused a huge latency across all CPUs. This was caused by only having one CPU having overloaded RT tasks and a bunch of other CPUs lowering their priority. To solve this issue, commit: b6366f048e0c ("sched/rt: Use IPI to trigger RT task push migration instead of pulling") changed the way to request a pull. Instead of grabbing the lock of the overloaded CPU's runqueue, it simply sent an IPI to that CPU to do the work. Although the IPI logic worked very well in removing the large latency build up, it still could suffer from a large number of IPIs being sent to a single CPU. On a 80 CPU box, I measured over 200us of processing IPIs. Worse yet, when I tested this on a 120 CPU box, with a stress test that had lots of RT tasks scheduling on all CPUs, it actually triggered the hard lockup detector! One CPU had so many IPIs sent to it, and due to the restart mechanism that is triggered when the source run queue has a priority status change, the CPU spent minutes! processing the IPIs. Thinking about this further, I realized there's no reason for each run queue to send its own IPI. As all CPUs with overloaded tasks must be scanned regardless if there's one or many CPUs lowering their priority, because there's no current way to find the CPU with the highest priority task that can schedule to one of these CPUs, there really only needs to be one IPI being sent around at a time. This greatly simplifies the code! The new approach is to have each root domain have its own irq work, as the rto_mask is per root domain. The root domain has the following fields attached to it: rto_push_work - the irq work to process each CPU set in rto_mask rto_lock - the lock to protect some of the other rto fields rto_loop_start - an atomic that keeps contention down on rto_lock the first CPU scheduling in a lower priority task is the one to kick off the process. rto_loop_next - an atomic that gets incremented for each CPU that schedules in a lower priority task. rto_loop - a variable protected by rto_lock that is used to compare against rto_loop_next rto_cpu - The cpu to send the next IPI to, also protected by the rto_lock. When a CPU schedules in a lower priority task and wants to make sure overloaded CPUs know about it. It increments the rto_loop_next. Then it atomically sets rto_loop_start with a cmpxchg. If the old value is not "0", then it is done, as another CPU is kicking off the IPI loop. If the old value is "0", then it will take the rto_lock to synchronize with a possible IPI being sent around to the overloaded CPUs. If rto_cpu is greater than or equal to nr_cpu_ids, then there's either no IPI being sent around, or one is about to finish. Then rto_cpu is set to the first CPU in rto_mask and an IPI is sent to that CPU. If there's no CPUs set in rto_mask, then there's nothing to be done. When the CPU receives the IPI, it will first try to push any RT tasks that is queued on the CPU but can't run because a higher priority RT task is currently running on that CPU. Then it takes the rto_lock and looks for the next CPU in the rto_mask. If it finds one, it simply sends an IPI to that CPU and the process continues. If there's no more CPUs in the rto_mask, then rto_loop is compared with rto_loop_next. If they match, everything is done and the process is over. If they do not match, then a CPU scheduled in a lower priority task as the IPI was being passed around, and the process needs to start again. The first CPU in rto_mask is sent the IPI. This change removes this duplication of work in the IPI logic, and greatly lowers the latency caused by the IPIs. This removed the lockup happening on the 120 CPU machine. It also simplifies the code tremendously. What else could anyone ask for? Thanks to Peter Zijlstra for simplifying the rto_loop_start atomic logic and supplying me with the rto_start_trylock() and rto_start_unlock() helper functions. Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Cc: Clark Williams <williams(a)redhat.com> Cc: Daniel Bristot de Oliveira <bristot(a)redhat.com> Cc: John Kacur <jkacur(a)redhat.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Mike Galbraith <efault(a)gmx.de> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Scott Wood <swood(a)redhat.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Link: http://lkml.kernel.org/r/20170424114732.1aac6dc4@gandalf.local.home Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- kernel/sched/core.c | 6 + kernel/sched/rt.c | 235 ++++++++++++++++++++++++--------------------------- kernel/sched/sched.h | 24 +++-- 3 files changed, 138 insertions(+), 127 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5907,6 +5907,12 @@ static int init_rootdomain(struct root_d if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) goto free_dlo_mask; +#ifdef HAVE_RT_PUSH_IPI + rd->rto_cpu = -1; + raw_spin_lock_init(&rd->rto_lock); + init_irq_work(&rd->rto_push_work, rto_push_irq_work_func); +#endif + init_dl_bw(&rd->dl_bw); if (cpudl_init(&rd->cpudl) != 0) goto free_dlo_mask; --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -64,10 +64,6 @@ static void start_rt_bandwidth(struct rt raw_spin_unlock(&rt_b->rt_runtime_lock); } -#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI) -static void push_irq_work_func(struct irq_work *work); -#endif - void init_rt_rq(struct rt_rq *rt_rq) { struct rt_prio_array *array; @@ -87,13 +83,6 @@ void init_rt_rq(struct rt_rq *rt_rq) rt_rq->rt_nr_migratory = 0; rt_rq->overloaded = 0; plist_head_init(&rt_rq->pushable_tasks); - -#ifdef HAVE_RT_PUSH_IPI - rt_rq->push_flags = 0; - rt_rq->push_cpu = nr_cpu_ids; - raw_spin_lock_init(&rt_rq->push_lock); - init_irq_work(&rt_rq->push_work, push_irq_work_func); -#endif #endif /* CONFIG_SMP */ /* We start is dequeued state, because no RT tasks are queued */ rt_rq->rt_queued = 0; @@ -1802,160 +1791,166 @@ static void push_rt_tasks(struct rq *rq) } #ifdef HAVE_RT_PUSH_IPI + /* - * The search for the next cpu always starts at rq->cpu and ends - * when we reach rq->cpu again. It will never return rq->cpu. - * This returns the next cpu to check, or nr_cpu_ids if the loop - * is complete. + * When a high priority task schedules out from a CPU and a lower priority + * task is scheduled in, a check is made to see if there's any RT tasks + * on other CPUs that are waiting to run because a higher priority RT task + * is currently running on its CPU. In this case, the CPU with multiple RT + * tasks queued on it (overloaded) needs to be notified that a CPU has opened + * up that may be able to run one of its non-running queued RT tasks. + * + * All CPUs with overloaded RT tasks need to be notified as there is currently + * no way to know which of these CPUs have the highest priority task waiting + * to run. Instead of trying to take a spinlock on each of these CPUs, + * which has shown to cause large latency when done on machines with many + * CPUs, sending an IPI to the CPUs to have them push off the overloaded + * RT tasks waiting to run. + * + * Just sending an IPI to each of the CPUs is also an issue, as on large + * count CPU machines, this can cause an IPI storm on a CPU, especially + * if its the only CPU with multiple RT tasks queued, and a large number + * of CPUs scheduling a lower priority task at the same time. + * + * Each root domain has its own irq work function that can iterate over + * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT + * tassk must be checked if there's one or many CPUs that are lowering + * their priority, there's a single irq work iterator that will try to + * push off RT tasks that are waiting to run. + * + * When a CPU schedules a lower priority task, it will kick off the + * irq work iterator that will jump to each CPU with overloaded RT tasks. + * As it only takes the first CPU that schedules a lower priority task + * to start the process, the rto_start variable is incremented and if + * the atomic result is one, then that CPU will try to take the rto_lock. + * This prevents high contention on the lock as the process handles all + * CPUs scheduling lower priority tasks. + * + * All CPUs that are scheduling a lower priority task will increment the + * rt_loop_next variable. This will make sure that the irq work iterator + * checks all RT overloaded CPUs whenever a CPU schedules a new lower + * priority task, even if the iterator is in the middle of a scan. Incrementing + * the rt_loop_next will cause the iterator to perform another scan. * - * rq->rt.push_cpu holds the last cpu returned by this function, - * or if this is the first instance, it must hold rq->cpu. */ static int rto_next_cpu(struct rq *rq) { - int prev_cpu = rq->rt.push_cpu; + struct root_domain *rd = rq->rd; + int next; int cpu; - cpu = cpumask_next(prev_cpu, rq->rd->rto_mask); - /* - * If the previous cpu is less than the rq's CPU, then it already - * passed the end of the mask, and has started from the beginning. - * We end if the next CPU is greater or equal to rq's CPU. + * When starting the IPI RT pushing, the rto_cpu is set to -1, + * rt_next_cpu() will simply return the first CPU found in + * the rto_mask. + * + * If rto_next_cpu() is called with rto_cpu is a valid cpu, it + * will return the next CPU found in the rto_mask. + * + * If there are no more CPUs left in the rto_mask, then a check is made + * against rto_loop and rto_loop_next. rto_loop is only updated with + * the rto_lock held, but any CPU may increment the rto_loop_next + * without any locking. */ - if (prev_cpu < rq->cpu) { - if (cpu >= rq->cpu) - return nr_cpu_ids; + for (;;) { - } else if (cpu >= nr_cpu_ids) { - /* - * We passed the end of the mask, start at the beginning. - * If the result is greater or equal to the rq's CPU, then - * the loop is finished. - */ - cpu = cpumask_first(rq->rd->rto_mask); - if (cpu >= rq->cpu) - return nr_cpu_ids; - } - rq->rt.push_cpu = cpu; + /* When rto_cpu is -1 this acts like cpumask_first() */ + cpu = cpumask_next(rd->rto_cpu, rd->rto_mask); - /* Return cpu to let the caller know if the loop is finished or not */ - return cpu; -} + rd->rto_cpu = cpu; -static int find_next_push_cpu(struct rq *rq) -{ - struct rq *next_rq; - int cpu; + if (cpu < nr_cpu_ids) + return cpu; - while (1) { - cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - break; - next_rq = cpu_rq(cpu); + rd->rto_cpu = -1; + + /* + * ACQUIRE ensures we see the @rto_mask changes + * made prior to the @next value observed. + * + * Matches WMB in rt_set_overload(). + */ + next = atomic_read_acquire(&rd->rto_loop_next); - /* Make sure the next rq can push to this rq */ - if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr) + if (rd->rto_loop == next) break; + + rd->rto_loop = next; } - return cpu; + return -1; } -#define RT_PUSH_IPI_EXECUTING 1 -#define RT_PUSH_IPI_RESTART 2 +static inline bool rto_start_trylock(atomic_t *v) +{ + return !atomic_cmpxchg_acquire(v, 0, 1); +} -static void tell_cpu_to_push(struct rq *rq) +static inline void rto_start_unlock(atomic_t *v) { - int cpu; + atomic_set_release(v, 0); +} - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - raw_spin_lock(&rq->rt.push_lock); - /* Make sure it's still executing */ - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - /* - * Tell the IPI to restart the loop as things have - * changed since it started. - */ - rq->rt.push_flags |= RT_PUSH_IPI_RESTART; - raw_spin_unlock(&rq->rt.push_lock); - return; - } - raw_spin_unlock(&rq->rt.push_lock); - } +static void tell_cpu_to_push(struct rq *rq) +{ + int cpu = -1; - /* When here, there's no IPI going around */ + /* Keep the loop going if the IPI is currently active */ + atomic_inc(&rq->rd->rto_loop_next); - rq->rt.push_cpu = rq->cpu; - cpu = find_next_push_cpu(rq); - if (cpu >= nr_cpu_ids) + /* Only one CPU can initiate a loop at a time */ + if (!rto_start_trylock(&rq->rd->rto_loop_start)) return; - rq->rt.push_flags = RT_PUSH_IPI_EXECUTING; + raw_spin_lock(&rq->rd->rto_lock); + + /* + * The rto_cpu is updated under the lock, if it has a valid cpu + * then the IPI is still running and will continue due to the + * update to loop_next, and nothing needs to be done here. + * Otherwise it is finishing up and an ipi needs to be sent. + */ + if (rq->rd->rto_cpu < 0) + cpu = rto_next_cpu(rq); + + raw_spin_unlock(&rq->rd->rto_lock); - irq_work_queue_on(&rq->rt.push_work, cpu); + rto_start_unlock(&rq->rd->rto_loop_start); + + if (cpu >= 0) + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } /* Called from hardirq context */ -static void try_to_push_tasks(void *arg) +void rto_push_irq_work_func(struct irq_work *work) { - struct rt_rq *rt_rq = arg; - struct rq *rq, *src_rq; - int this_cpu; + struct rq *rq; int cpu; - this_cpu = rt_rq->push_cpu; + rq = this_rq(); - /* Paranoid check */ - BUG_ON(this_cpu != smp_processor_id()); - - rq = cpu_rq(this_cpu); - src_rq = rq_of_rt_rq(rt_rq); - -again: + /* + * We do not need to grab the lock to check for has_pushable_tasks. + * When it gets updated, a check is made if a push is possible. + */ if (has_pushable_tasks(rq)) { raw_spin_lock(&rq->lock); - push_rt_task(rq); + push_rt_tasks(rq); raw_spin_unlock(&rq->lock); } - /* Pass the IPI to the next rt overloaded queue */ - raw_spin_lock(&rt_rq->push_lock); - /* - * If the source queue changed since the IPI went out, - * we need to restart the search from that CPU again. - */ - if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) { - rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART; - rt_rq->push_cpu = src_rq->cpu; - } + raw_spin_lock(&rq->rd->rto_lock); - cpu = find_next_push_cpu(src_rq); + /* Pass the IPI to the next rt overloaded queue */ + cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING; - raw_spin_unlock(&rt_rq->push_lock); + raw_spin_unlock(&rq->rd->rto_lock); - if (cpu >= nr_cpu_ids) + if (cpu < 0) return; - /* - * It is possible that a restart caused this CPU to be - * chosen again. Don't bother with an IPI, just see if we - * have more to push. - */ - if (unlikely(cpu == rq->cpu)) - goto again; - /* Try the next RT overloaded CPU */ - irq_work_queue_on(&rt_rq->push_work, cpu); -} - -static void push_irq_work_func(struct irq_work *work) -{ - struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work); - - try_to_push_tasks(rt_rq); + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } #endif /* HAVE_RT_PUSH_IPI */ --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -429,7 +429,7 @@ static inline int rt_bandwidth_enabled(v } /* RT IPI pull logic requires IRQ_WORK */ -#ifdef CONFIG_IRQ_WORK +#if defined(CONFIG_IRQ_WORK) && defined(CONFIG_SMP) # define HAVE_RT_PUSH_IPI #endif @@ -450,12 +450,6 @@ struct rt_rq { unsigned long rt_nr_total; int overloaded; struct plist_head pushable_tasks; -#ifdef HAVE_RT_PUSH_IPI - int push_flags; - int push_cpu; - struct irq_work push_work; - raw_spinlock_t push_lock; -#endif #endif /* CONFIG_SMP */ int rt_queued; @@ -537,6 +531,19 @@ struct root_domain { struct dl_bw dl_bw; struct cpudl cpudl; +#ifdef HAVE_RT_PUSH_IPI + /* + * For IPI pull requests, loop across the rto_mask. + */ + struct irq_work rto_push_work; + raw_spinlock_t rto_lock; + /* These are only updated and read within rto_lock */ + int rto_loop; + int rto_cpu; + /* These atomics are updated outside of a lock */ + atomic_t rto_loop_next; + atomic_t rto_loop_start; +#endif /* * The "RT overload" flag: it gets set if a CPU has more than * one runnable RT task. @@ -547,6 +554,9 @@ struct root_domain { extern struct root_domain def_root_domain; +#ifdef HAVE_RT_PUSH_IPI +extern void rto_push_irq_work_func(struct irq_work *work); +#endif #endif /* CONFIG_SMP */ /* Patches currently in stable-queue which might be from rostedt(a)goodmis.org are queue-4.4/sched-make-resched_cpu-unconditional.patch queue-4.4/sched-rt-simplify-the-ipi-based-rt-balancing-logic.patch

7 years, 7 months

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[Linux-stable-mirror] FAILED: patch "[PATCH] sched/rt: Simplify the IPI based RT balancing logic" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 4bdced5c9a2922521e325896a7bbbf0132c94e56 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" <rostedt(a)goodmis.org> Date: Fri, 6 Oct 2017 14:05:04 -0400 Subject: [PATCH] sched/rt: Simplify the IPI based RT balancing logic When a CPU lowers its priority (schedules out a high priority task for a lower priority one), a check is made to see if any other CPU has overloaded RT tasks (more than one). It checks the rto_mask to determine this and if so it will request to pull one of those tasks to itself if the non running RT task is of higher priority than the new priority of the next task to run on the current CPU. When we deal with large number of CPUs, the original pull logic suffered from large lock contention on a single CPU run queue, which caused a huge latency across all CPUs. This was caused by only having one CPU having overloaded RT tasks and a bunch of other CPUs lowering their priority. To solve this issue, commit: b6366f048e0c ("sched/rt: Use IPI to trigger RT task push migration instead of pulling") changed the way to request a pull. Instead of grabbing the lock of the overloaded CPU's runqueue, it simply sent an IPI to that CPU to do the work. Although the IPI logic worked very well in removing the large latency build up, it still could suffer from a large number of IPIs being sent to a single CPU. On a 80 CPU box, I measured over 200us of processing IPIs. Worse yet, when I tested this on a 120 CPU box, with a stress test that had lots of RT tasks scheduling on all CPUs, it actually triggered the hard lockup detector! One CPU had so many IPIs sent to it, and due to the restart mechanism that is triggered when the source run queue has a priority status change, the CPU spent minutes! processing the IPIs. Thinking about this further, I realized there's no reason for each run queue to send its own IPI. As all CPUs with overloaded tasks must be scanned regardless if there's one or many CPUs lowering their priority, because there's no current way to find the CPU with the highest priority task that can schedule to one of these CPUs, there really only needs to be one IPI being sent around at a time. This greatly simplifies the code! The new approach is to have each root domain have its own irq work, as the rto_mask is per root domain. The root domain has the following fields attached to it: rto_push_work - the irq work to process each CPU set in rto_mask rto_lock - the lock to protect some of the other rto fields rto_loop_start - an atomic that keeps contention down on rto_lock the first CPU scheduling in a lower priority task is the one to kick off the process. rto_loop_next - an atomic that gets incremented for each CPU that schedules in a lower priority task. rto_loop - a variable protected by rto_lock that is used to compare against rto_loop_next rto_cpu - The cpu to send the next IPI to, also protected by the rto_lock. When a CPU schedules in a lower priority task and wants to make sure overloaded CPUs know about it. It increments the rto_loop_next. Then it atomically sets rto_loop_start with a cmpxchg. If the old value is not "0", then it is done, as another CPU is kicking off the IPI loop. If the old value is "0", then it will take the rto_lock to synchronize with a possible IPI being sent around to the overloaded CPUs. If rto_cpu is greater than or equal to nr_cpu_ids, then there's either no IPI being sent around, or one is about to finish. Then rto_cpu is set to the first CPU in rto_mask and an IPI is sent to that CPU. If there's no CPUs set in rto_mask, then there's nothing to be done. When the CPU receives the IPI, it will first try to push any RT tasks that is queued on the CPU but can't run because a higher priority RT task is currently running on that CPU. Then it takes the rto_lock and looks for the next CPU in the rto_mask. If it finds one, it simply sends an IPI to that CPU and the process continues. If there's no more CPUs in the rto_mask, then rto_loop is compared with rto_loop_next. If they match, everything is done and the process is over. If they do not match, then a CPU scheduled in a lower priority task as the IPI was being passed around, and the process needs to start again. The first CPU in rto_mask is sent the IPI. This change removes this duplication of work in the IPI logic, and greatly lowers the latency caused by the IPIs. This removed the lockup happening on the 120 CPU machine. It also simplifies the code tremendously. What else could anyone ask for? Thanks to Peter Zijlstra for simplifying the rto_loop_start atomic logic and supplying me with the rto_start_trylock() and rto_start_unlock() helper functions. Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Cc: Clark Williams <williams(a)redhat.com> Cc: Daniel Bristot de Oliveira <bristot(a)redhat.com> Cc: John Kacur <jkacur(a)redhat.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Mike Galbraith <efault(a)gmx.de> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Scott Wood <swood(a)redhat.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Link: http://lkml.kernel.org/r/20170424114732.1aac6dc4@gandalf.local.home Signed-off-by: Ingo Molnar <mingo(a)kernel.org> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 0af5ca9e3e3f..fda27991699a 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -73,10 +73,6 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b) raw_spin_unlock(&rt_b->rt_runtime_lock); } -#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI) -static void push_irq_work_func(struct irq_work *work); -#endif - void init_rt_rq(struct rt_rq *rt_rq) { struct rt_prio_array *array; @@ -96,13 +92,6 @@ void init_rt_rq(struct rt_rq *rt_rq) rt_rq->rt_nr_migratory = 0; rt_rq->overloaded = 0; plist_head_init(&rt_rq->pushable_tasks); - -#ifdef HAVE_RT_PUSH_IPI - rt_rq->push_flags = 0; - rt_rq->push_cpu = nr_cpu_ids; - raw_spin_lock_init(&rt_rq->push_lock); - init_irq_work(&rt_rq->push_work, push_irq_work_func); -#endif #endif /* CONFIG_SMP */ /* We start is dequeued state, because no RT tasks are queued */ rt_rq->rt_queued = 0; @@ -1875,241 +1864,166 @@ static void push_rt_tasks(struct rq *rq) } #ifdef HAVE_RT_PUSH_IPI + /* - * The search for the next cpu always starts at rq->cpu and ends - * when we reach rq->cpu again. It will never return rq->cpu. - * This returns the next cpu to check, or nr_cpu_ids if the loop - * is complete. + * When a high priority task schedules out from a CPU and a lower priority + * task is scheduled in, a check is made to see if there's any RT tasks + * on other CPUs that are waiting to run because a higher priority RT task + * is currently running on its CPU. In this case, the CPU with multiple RT + * tasks queued on it (overloaded) needs to be notified that a CPU has opened + * up that may be able to run one of its non-running queued RT tasks. + * + * All CPUs with overloaded RT tasks need to be notified as there is currently + * no way to know which of these CPUs have the highest priority task waiting + * to run. Instead of trying to take a spinlock on each of these CPUs, + * which has shown to cause large latency when done on machines with many + * CPUs, sending an IPI to the CPUs to have them push off the overloaded + * RT tasks waiting to run. + * + * Just sending an IPI to each of the CPUs is also an issue, as on large + * count CPU machines, this can cause an IPI storm on a CPU, especially + * if its the only CPU with multiple RT tasks queued, and a large number + * of CPUs scheduling a lower priority task at the same time. + * + * Each root domain has its own irq work function that can iterate over + * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT + * tassk must be checked if there's one or many CPUs that are lowering + * their priority, there's a single irq work iterator that will try to + * push off RT tasks that are waiting to run. + * + * When a CPU schedules a lower priority task, it will kick off the + * irq work iterator that will jump to each CPU with overloaded RT tasks. + * As it only takes the first CPU that schedules a lower priority task + * to start the process, the rto_start variable is incremented and if + * the atomic result is one, then that CPU will try to take the rto_lock. + * This prevents high contention on the lock as the process handles all + * CPUs scheduling lower priority tasks. + * + * All CPUs that are scheduling a lower priority task will increment the + * rt_loop_next variable. This will make sure that the irq work iterator + * checks all RT overloaded CPUs whenever a CPU schedules a new lower + * priority task, even if the iterator is in the middle of a scan. Incrementing + * the rt_loop_next will cause the iterator to perform another scan. * - * rq->rt.push_cpu holds the last cpu returned by this function, - * or if this is the first instance, it must hold rq->cpu. */ static int rto_next_cpu(struct rq *rq) { - int prev_cpu = rq->rt.push_cpu; + struct root_domain *rd = rq->rd; + int next; int cpu; - cpu = cpumask_next(prev_cpu, rq->rd->rto_mask); - /* - * If the previous cpu is less than the rq's CPU, then it already - * passed the end of the mask, and has started from the beginning. - * We end if the next CPU is greater or equal to rq's CPU. + * When starting the IPI RT pushing, the rto_cpu is set to -1, + * rt_next_cpu() will simply return the first CPU found in + * the rto_mask. + * + * If rto_next_cpu() is called with rto_cpu is a valid cpu, it + * will return the next CPU found in the rto_mask. + * + * If there are no more CPUs left in the rto_mask, then a check is made + * against rto_loop and rto_loop_next. rto_loop is only updated with + * the rto_lock held, but any CPU may increment the rto_loop_next + * without any locking. */ - if (prev_cpu < rq->cpu) { - if (cpu >= rq->cpu) - return nr_cpu_ids; + for (;;) { - } else if (cpu >= nr_cpu_ids) { - /* - * We passed the end of the mask, start at the beginning. - * If the result is greater or equal to the rq's CPU, then - * the loop is finished. - */ - cpu = cpumask_first(rq->rd->rto_mask); - if (cpu >= rq->cpu) - return nr_cpu_ids; - } - rq->rt.push_cpu = cpu; + /* When rto_cpu is -1 this acts like cpumask_first() */ + cpu = cpumask_next(rd->rto_cpu, rd->rto_mask); - /* Return cpu to let the caller know if the loop is finished or not */ - return cpu; -} + rd->rto_cpu = cpu; -static int find_next_push_cpu(struct rq *rq) -{ - struct rq *next_rq; - int cpu; + if (cpu < nr_cpu_ids) + return cpu; - while (1) { - cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - break; - next_rq = cpu_rq(cpu); + rd->rto_cpu = -1; + + /* + * ACQUIRE ensures we see the @rto_mask changes + * made prior to the @next value observed. + * + * Matches WMB in rt_set_overload(). + */ + next = atomic_read_acquire(&rd->rto_loop_next); - /* Make sure the next rq can push to this rq */ - if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr) + if (rd->rto_loop == next) break; + + rd->rto_loop = next; } - return cpu; + return -1; } -#define RT_PUSH_IPI_EXECUTING 1 -#define RT_PUSH_IPI_RESTART 2 +static inline bool rto_start_trylock(atomic_t *v) +{ + return !atomic_cmpxchg_acquire(v, 0, 1); +} -/* - * When a high priority task schedules out from a CPU and a lower priority - * task is scheduled in, a check is made to see if there's any RT tasks - * on other CPUs that are waiting to run because a higher priority RT task - * is currently running on its CPU. In this case, the CPU with multiple RT - * tasks queued on it (overloaded) needs to be notified that a CPU has opened - * up that may be able to run one of its non-running queued RT tasks. - * - * On large CPU boxes, there's the case that several CPUs could schedule - * a lower priority task at the same time, in which case it will look for - * any overloaded CPUs that it could pull a task from. To do this, the runqueue - * lock must be taken from that overloaded CPU. Having 10s of CPUs all fighting - * for a single overloaded CPU's runqueue lock can produce a large latency. - * (This has actually been observed on large boxes running cyclictest). - * Instead of taking the runqueue lock of the overloaded CPU, each of the - * CPUs that scheduled a lower priority task simply sends an IPI to the - * overloaded CPU. An IPI is much cheaper than taking an runqueue lock with - * lots of contention. The overloaded CPU will look to push its non-running - * RT task off, and if it does, it can then ignore the other IPIs coming - * in, and just pass those IPIs off to any other overloaded CPU. - * - * When a CPU schedules a lower priority task, it only sends an IPI to - * the "next" CPU that has overloaded RT tasks. This prevents IPI storms, - * as having 10 CPUs scheduling lower priority tasks and 10 CPUs with - * RT overloaded tasks, would cause 100 IPIs to go out at once. - * - * The overloaded RT CPU, when receiving an IPI, will try to push off its - * overloaded RT tasks and then send an IPI to the next CPU that has - * overloaded RT tasks. This stops when all CPUs with overloaded RT tasks - * have completed. Just because a CPU may have pushed off its own overloaded - * RT task does not mean it should stop sending the IPI around to other - * overloaded CPUs. There may be another RT task waiting to run on one of - * those CPUs that are of higher priority than the one that was just - * pushed. - * - * An optimization that could possibly be made is to make a CPU array similar - * to the cpupri array mask of all running RT tasks, but for the overloaded - * case, then the IPI could be sent to only the CPU with the highest priority - * RT task waiting, and that CPU could send off further IPIs to the CPU with - * the next highest waiting task. Since the overloaded case is much less likely - * to happen, the complexity of this implementation may not be worth it. - * Instead, just send an IPI around to all overloaded CPUs. - * - * The rq->rt.push_flags holds the status of the IPI that is going around. - * A run queue can only send out a single IPI at a time. The possible flags - * for rq->rt.push_flags are: - * - * (None or zero): No IPI is going around for the current rq - * RT_PUSH_IPI_EXECUTING: An IPI for the rq is being passed around - * RT_PUSH_IPI_RESTART: The priority of the running task for the rq - * has changed, and the IPI should restart - * circulating the overloaded CPUs again. - * - * rq->rt.push_cpu contains the CPU that is being sent the IPI. It is updated - * before sending to the next CPU. - * - * Instead of having all CPUs that schedule a lower priority task send - * an IPI to the same "first" CPU in the RT overload mask, they send it - * to the next overloaded CPU after their own CPU. This helps distribute - * the work when there's more than one overloaded CPU and multiple CPUs - * scheduling in lower priority tasks. - * - * When a rq schedules a lower priority task than what was currently - * running, the next CPU with overloaded RT tasks is examined first. - * That is, if CPU 1 and 5 are overloaded, and CPU 3 schedules a lower - * priority task, it will send an IPI first to CPU 5, then CPU 5 will - * send to CPU 1 if it is still overloaded. CPU 1 will clear the - * rq->rt.push_flags if RT_PUSH_IPI_RESTART is not set. - * - * The first CPU to notice IPI_RESTART is set, will clear that flag and then - * send an IPI to the next overloaded CPU after the rq->cpu and not the next - * CPU after push_cpu. That is, if CPU 1, 4 and 5 are overloaded when CPU 3 - * schedules a lower priority task, and the IPI_RESTART gets set while the - * handling is being done on CPU 5, it will clear the flag and send it back to - * CPU 4 instead of CPU 1. - * - * Note, the above logic can be disabled by turning off the sched_feature - * RT_PUSH_IPI. Then the rq lock of the overloaded CPU will simply be - * taken by the CPU requesting a pull and the waiting RT task will be pulled - * by that CPU. This may be fine for machines with few CPUs. - */ -static void tell_cpu_to_push(struct rq *rq) +static inline void rto_start_unlock(atomic_t *v) { - int cpu; + atomic_set_release(v, 0); +} - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - raw_spin_lock(&rq->rt.push_lock); - /* Make sure it's still executing */ - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - /* - * Tell the IPI to restart the loop as things have - * changed since it started. - */ - rq->rt.push_flags |= RT_PUSH_IPI_RESTART; - raw_spin_unlock(&rq->rt.push_lock); - return; - } - raw_spin_unlock(&rq->rt.push_lock); - } +static void tell_cpu_to_push(struct rq *rq) +{ + int cpu = -1; - /* When here, there's no IPI going around */ + /* Keep the loop going if the IPI is currently active */ + atomic_inc(&rq->rd->rto_loop_next); - rq->rt.push_cpu = rq->cpu; - cpu = find_next_push_cpu(rq); - if (cpu >= nr_cpu_ids) + /* Only one CPU can initiate a loop at a time */ + if (!rto_start_trylock(&rq->rd->rto_loop_start)) return; - rq->rt.push_flags = RT_PUSH_IPI_EXECUTING; + raw_spin_lock(&rq->rd->rto_lock); + + /* + * The rto_cpu is updated under the lock, if it has a valid cpu + * then the IPI is still running and will continue due to the + * update to loop_next, and nothing needs to be done here. + * Otherwise it is finishing up and an ipi needs to be sent. + */ + if (rq->rd->rto_cpu < 0) + cpu = rto_next_cpu(rq); - irq_work_queue_on(&rq->rt.push_work, cpu); + raw_spin_unlock(&rq->rd->rto_lock); + + rto_start_unlock(&rq->rd->rto_loop_start); + + if (cpu >= 0) + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } /* Called from hardirq context */ -static void try_to_push_tasks(void *arg) +void rto_push_irq_work_func(struct irq_work *work) { - struct rt_rq *rt_rq = arg; - struct rq *rq, *src_rq; - int this_cpu; + struct rq *rq; int cpu; - this_cpu = rt_rq->push_cpu; + rq = this_rq(); - /* Paranoid check */ - BUG_ON(this_cpu != smp_processor_id()); - - rq = cpu_rq(this_cpu); - src_rq = rq_of_rt_rq(rt_rq); - -again: + /* + * We do not need to grab the lock to check for has_pushable_tasks. + * When it gets updated, a check is made if a push is possible. + */ if (has_pushable_tasks(rq)) { raw_spin_lock(&rq->lock); - push_rt_task(rq); + push_rt_tasks(rq); raw_spin_unlock(&rq->lock); } - /* Pass the IPI to the next rt overloaded queue */ - raw_spin_lock(&rt_rq->push_lock); - /* - * If the source queue changed since the IPI went out, - * we need to restart the search from that CPU again. - */ - if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) { - rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART; - rt_rq->push_cpu = src_rq->cpu; - } + raw_spin_lock(&rq->rd->rto_lock); - cpu = find_next_push_cpu(src_rq); + /* Pass the IPI to the next rt overloaded queue */ + cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING; - raw_spin_unlock(&rt_rq->push_lock); + raw_spin_unlock(&rq->rd->rto_lock); - if (cpu >= nr_cpu_ids) + if (cpu < 0) return; - /* - * It is possible that a restart caused this CPU to be - * chosen again. Don't bother with an IPI, just see if we - * have more to push. - */ - if (unlikely(cpu == rq->cpu)) - goto again; - /* Try the next RT overloaded CPU */ - irq_work_queue_on(&rt_rq->push_work, cpu); -} - -static void push_irq_work_func(struct irq_work *work) -{ - struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work); - - try_to_push_tasks(rt_rq); + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } #endif /* HAVE_RT_PUSH_IPI */ diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a81c9782e98c..8aa24b41f652 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -505,7 +505,7 @@ static inline int rt_bandwidth_enabled(void) } /* RT IPI pull logic requires IRQ_WORK */ -#ifdef CONFIG_IRQ_WORK +#if defined(CONFIG_IRQ_WORK) && defined(CONFIG_SMP) # define HAVE_RT_PUSH_IPI #endif @@ -527,12 +527,6 @@ struct rt_rq { unsigned long rt_nr_total; int overloaded; struct plist_head pushable_tasks; -#ifdef HAVE_RT_PUSH_IPI - int push_flags; - int push_cpu; - struct irq_work push_work; - raw_spinlock_t push_lock; -#endif #endif /* CONFIG_SMP */ int rt_queued; @@ -641,6 +635,19 @@ struct root_domain { struct dl_bw dl_bw; struct cpudl cpudl; +#ifdef HAVE_RT_PUSH_IPI + /* + * For IPI pull requests, loop across the rto_mask. + */ + struct irq_work rto_push_work; + raw_spinlock_t rto_lock; + /* These are only updated and read within rto_lock */ + int rto_loop; + int rto_cpu; + /* These atomics are updated outside of a lock */ + atomic_t rto_loop_next; + atomic_t rto_loop_start; +#endif /* * The "RT overload" flag: it gets set if a CPU has more than * one runnable RT task. @@ -658,6 +665,9 @@ extern void init_defrootdomain(void); extern int sched_init_domains(const struct cpumask *cpu_map); extern void rq_attach_root(struct rq *rq, struct root_domain *rd); +#ifdef HAVE_RT_PUSH_IPI +extern void rto_push_irq_work_func(struct irq_work *work); +#endif #endif /* CONFIG_SMP */ /* diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index f51d123f9fe1..e50450c2fed8 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -268,6 +268,12 @@ static int init_rootdomain(struct root_domain *rd) if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) goto free_dlo_mask; +#ifdef HAVE_RT_PUSH_IPI + rd->rto_cpu = -1; + raw_spin_lock_init(&rd->rto_lock); + init_irq_work(&rd->rto_push_work, rto_push_irq_work_func); +#endif + init_dl_bw(&rd->dl_bw); if (cpudl_init(&rd->cpudl) != 0) goto free_rto_mask;

7 years, 7 months

3
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[Linux-stable-mirror] [PATCH v2] drm/i915/gvt: Correct ADDR_4K/2M/1G_MASK definition

by Xiong Zhang

For ADDR_4K_MASK, bit[45..12] should be 1, all other bits should be 0. The current definition wrongly set bit[46] as 1 also. This path fixes this. v2: Add commit message, fixes and cc stable.(Zhenyu) Fixes: 2707e4446688("drm/i915/gvt: vGPU graphics memory virtualization") Signed-off-by: Xiong Zhang <xiong.y.zhang(a)intel.com> Cc: stable(a)vger.kernel.org --- drivers/gpu/drm/i915/gvt/gtt.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 3d6008b..71a0f2b 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -331,9 +331,9 @@ static inline int gtt_set_entry64(void *pt, #define GTT_HAW 46 -#define ADDR_1G_MASK (((1UL << (GTT_HAW - 30 + 1)) - 1) << 30) -#define ADDR_2M_MASK (((1UL << (GTT_HAW - 21 + 1)) - 1) << 21) -#define ADDR_4K_MASK (((1UL << (GTT_HAW - 12 + 1)) - 1) << 12) +#define ADDR_1G_MASK (((1UL << (GTT_HAW - 30)) - 1) << 30) +#define ADDR_2M_MASK (((1UL << (GTT_HAW - 21)) - 1) << 21) +#define ADDR_4K_MASK (((1UL << (GTT_HAW - 12)) - 1) << 12) static unsigned long gen8_gtt_get_pfn(struct intel_gvt_gtt_entry *e) { -- 2.7.4

7 years, 7 months

1
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[Linux-stable-mirror] + mmmadvise-bugfix-of-madvise-systemcall-infinite-loop-under-special-circumstances.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: mm/madvise.c: fix madvise() infinite loop under special circumstances has been added to the -mm tree. Its filename is mmmadvise-bugfix-of-madvise-systemcall-infinite-loop-under-special-circumstances.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mmmadvise-bugfix-of-madvise-system… and later at http://ozlabs.org/~akpm/mmotm/broken-out/mmmadvise-bugfix-of-madvise-system… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: chenjie <chenjie6(a)huawei.com> Subject: mm/madvise.c: fix madvise() infinite loop under special circumstances MADVISE_WILLNEED has always been a noop for DAX (formerly XIP) mappings. Unfortunatelly madvise_willneed() doesn't communicate this information properly to the generic madvise syscall implementation. The calling convention is quite subtle there. madvise_vma() is supposed to either return an error or update &prev otherwise the main loop will never advance to the next vma and it will keep looping for ever without a way to get out of the kernel. It seems this has been broken since introduction. Nobody has noticed because nobody seems to be using MADVISE_WILLNEED on these DAX mappings. [mhocko(a)suse.com: rewrite changelog] Link: http://lkml.kernel.org/r/20171127115318.911-1-guoxuenan@huawei.com Fixes: fe77ba6f4f97 ("[PATCH] xip: madvice/fadvice: execute in place") Signed-off-by: chenjie <chenjie6(a)huawei.com> Signed-off-by: guoxuenan <guoxuenan(a)huawei.com> Acked-by: Michal Hocko <mhocko(a)suse.com> Cc: Minchan Kim <minchan(a)kernel.org> Cc: zhangyi (F) <yi.zhang(a)huawei.com> Cc: Miao Xie <miaoxie(a)huawei.com> Cc: Mike Rapoport <rppt(a)linux.vnet.ibm.com> Cc: Shaohua Li <shli(a)fb.com> Cc: Andrea Arcangeli <aarcange(a)redhat.com> Cc: Mel Gorman <mgorman(a)techsingularity.net> Cc: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com> Cc: David Rientjes <rientjes(a)google.com> Cc: Anshuman Khandual <khandual(a)linux.vnet.ibm.com> Cc: Rik van Riel <riel(a)redhat.com> Cc: Carsten Otte <cotte(a)de.ibm.com> Cc: Dan Williams <dan.j.williams(a)intel.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/madvise.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff -puN mm/madvise.c~mmmadvise-bugfix-of-madvise-systemcall-infinite-loop-under-special-circumstances mm/madvise.c --- a/mm/madvise.c~mmmadvise-bugfix-of-madvise-systemcall-infinite-loop-under-special-circumstances +++ a/mm/madvise.c @@ -276,15 +276,14 @@ static long madvise_willneed(struct vm_a { struct file *file = vma->vm_file; + *prev = vma; #ifdef CONFIG_SWAP if (!file) { - *prev = vma; force_swapin_readahead(vma, start, end); return 0; } if (shmem_mapping(file->f_mapping)) { - *prev = vma; force_shm_swapin_readahead(vma, start, end, file->f_mapping); return 0; @@ -299,7 +298,6 @@ static long madvise_willneed(struct vm_a return 0; } - *prev = vma; start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; if (end > vma->vm_end) end = vma->vm_end; _ Patches currently in -mm which might be from chenjie6(a)huawei.com are mmmadvise-bugfix-of-madvise-systemcall-infinite-loop-under-special-circumstances.patch

7 years, 7 months

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[Linux-stable-mirror] + exec-avoid-rlimit_stack-races-with-prlimit.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: exec: avoid RLIMIT_STACK races with prlimit() has been added to the -mm tree. Its filename is exec-avoid-rlimit_stack-races-with-prlimit.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/exec-avoid-rlimit_stack-races-with… and later at http://ozlabs.org/~akpm/mmotm/broken-out/exec-avoid-rlimit_stack-races-with… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Kees Cook <keescook(a)chromium.org> Subject: exec: avoid RLIMIT_STACK races with prlimit() While the defense-in-depth RLIMIT_STACK limit on setuid processes was protected against races from other threads calling setrlimit(), I missed protecting it against races from external processes calling prlimit(). This adds locking around the change and makes sure that rlim_max is set too. Link: http://lkml.kernel.org/r/20171127193457.GA11348@beast Fixes: 64701dee4178e ("exec: Use sane stack rlimit under secureexec") Signed-off-by: Kees Cook <keescook(a)chromium.org> Reported-by: Ben Hutchings <ben.hutchings(a)codethink.co.uk> Reported-by: Brad Spengler <spender(a)grsecurity.net> Cc: James Morris <james.l.morris(a)oracle.com> Cc: Serge Hallyn <serge(a)hallyn.com> Cc: Andy Lutomirski <luto(a)kernel.org> Cc: Oleg Nesterov <oleg(a)redhat.com> Cc: Jiri Slaby <jslaby(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/exec.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff -puN fs/exec.c~exec-avoid-rlimit_stack-races-with-prlimit fs/exec.c --- a/fs/exec.c~exec-avoid-rlimit_stack-races-with-prlimit +++ a/fs/exec.c @@ -1340,10 +1340,15 @@ void setup_new_exec(struct linux_binprm * avoid bad behavior from the prior rlimits. This has to * happen before arch_pick_mmap_layout(), which examines * RLIMIT_STACK, but after the point of no return to avoid - * needing to clean up the change on failure. + * races from other threads changing the limits. This also + * must be protected from races with prlimit() calls. */ + task_lock(current->group_leader); if (current->signal->rlim[RLIMIT_STACK].rlim_cur > _STK_LIM) current->signal->rlim[RLIMIT_STACK].rlim_cur = _STK_LIM; + if (current->signal->rlim[RLIMIT_STACK].rlim_max > _STK_LIM) + current->signal->rlim[RLIMIT_STACK].rlim_max = _STK_LIM; + task_unlock(current->group_leader); } arch_pick_mmap_layout(current->mm); _ Patches currently in -mm which might be from keescook(a)chromium.org are exec-avoid-rlimit_stack-races-with-prlimit.patch makefile-move-stack-protector-compiler-breakage-test-earlier.patch makefile-move-stack-protector-availability-out-of-kconfig.patch makefile-introduce-config_cc_stackprotector_auto.patch

7 years, 7 months

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[Linux-stable-mirror] [PATCH v2] drm/i915/gvt: Correct ADDR_4K/2M/1G_MASK definition

by Xiong Zhang

For ADDR_4K_MASK, bit[45..12] should be 1, all other bits should be 0. The current definition wrongly set bit[46] as 1 also. This path fixes this. v2: Add commit message, fixes and cc stable.(Zhenyu) Fixes: 2707e4446688("drm/i915/gvt: vGPU graphics memory virtualization") Signed-off-by: Xiong Zhang <xiong.y.zhang(a)intel.com> --- drivers/gpu/drm/i915/gvt/gtt.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 3d6008b..71a0f2b 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -331,9 +331,9 @@ static inline int gtt_set_entry64(void *pt, #define GTT_HAW 46 -#define ADDR_1G_MASK (((1UL << (GTT_HAW - 30 + 1)) - 1) << 30) -#define ADDR_2M_MASK (((1UL << (GTT_HAW - 21 + 1)) - 1) << 21) -#define ADDR_4K_MASK (((1UL << (GTT_HAW - 12 + 1)) - 1) << 12) +#define ADDR_1G_MASK (((1UL << (GTT_HAW - 30)) - 1) << 30) +#define ADDR_2M_MASK (((1UL << (GTT_HAW - 21)) - 1) << 21) +#define ADDR_4K_MASK (((1UL << (GTT_HAW - 12)) - 1) << 12) static unsigned long gen8_gtt_get_pfn(struct intel_gvt_gtt_entry *e) { -- 2.7.4

7 years, 7 months

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[Linux-stable-mirror] [PATCH 4.1] fscrypt: lock mutex before checking for bounce page pool

by Eric Biggers

commit a0b3bc855374c50b5ea85273553485af48caf2f7 upstream. [Please apply to 4.1-stable.] fscrypt_initialize(), which allocates the global bounce page pool when an encrypted file is first accessed, uses "double-checked locking" to try to avoid locking fscrypt_init_mutex. However, it doesn't use any memory barriers, so it's theoretically possible for a thread to observe a bounce page pool which has not been fully initialized. This is a classic bug with "double-checked locking". While "only a theoretical issue" in the latest kernel, in pre-4.8 kernels the pointer that was checked was not even the last to be initialized, so it was easily possible for a crash (NULL pointer dereference) to happen. This was changed only incidentally by the large refactor to use fs/crypto/. Solve both problems in a trivial way that can easily be backported: just always take the mutex. It's theoretically less efficient, but it shouldn't be noticeable in practice as the mutex is only acquired very briefly once per encrypted file. Later I'd like to make this use a helper macro like DO_ONCE(). However, DO_ONCE() runs in atomic context, so we'd need to add a new macro that allows blocking. Cc: stable(a)vger.kernel.org # v4.1+ Signed-off-by: Eric Biggers <ebiggers(a)google.com> Signed-off-by: Theodore Ts'o <tytso(a)mit.edu> --- fs/ext4/crypto.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c index 8ff15273ab0c..fdda7a5a1180 100644 --- a/fs/ext4/crypto.c +++ b/fs/ext4/crypto.c @@ -120,8 +120,7 @@ struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode) unsigned long flags; struct ext4_encryption_key *key = &EXT4_I(inode)->i_encryption_key; - if (!ext4_read_workqueue) - ext4_init_crypto(); + ext4_init_crypto(); /* * We first try getting the ctx from a free list because in -- 2.15.0.417.g466bffb3ac-goog

7 years, 7 months

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[Linux-stable-mirror] [PATCH] eeprom: at24: fix the magic value for at24mac402

by Bartosz Golaszewski

There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6, making it impossible to read it all. Fix it by creating the magic value manually with the correct size. This patch contains a temporary fix that is suitable for stable branches. Eventually we'll probably remove the call to ilog2() while converting the magic values to actual structs. This fix will cause a warning message to be emitted by probe() for at24mac402 chips but theys should be initialized correctly anyway. Cc: stable(a)vger.kernel.org Fixes: 0b813658c115 ("eeprom: at24: add support for at24mac series") Signed-off-by: Bartosz Golaszewski <brgl(a)bgdev.pl> --- drivers/misc/eeprom/at24.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index e0b4b36ef010..72adf34627f5 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -141,8 +141,17 @@ static const struct i2c_device_id at24_ids[] = { { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) }, { "24cs02", AT24_DEVICE_MAGIC(16, AT24_FLAG_SERIAL | AT24_FLAG_READONLY) }, - { "24mac402", AT24_DEVICE_MAGIC(48 / 8, - AT24_FLAG_MAC | AT24_FLAG_READONLY) }, + /* + * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while + * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4. We + * might want to eventually remove it altogether or maybe even convert + * the magic values to real structs. + * + * For now just create the magic value manually with the right size. + */ + { "24mac402", ((1 << AT24_SIZE_FLAGS | + (AT24_FLAG_MAC | AT24_FLAG_READONLY)) + << AT24_SIZE_BYTELEN | (48 / 8)) }, { "24mac602", AT24_DEVICE_MAGIC(64 / 8, AT24_FLAG_MAC | AT24_FLAG_READONLY) }, /* spd is a 24c02 in memory DIMMs */ -- 2.15.0

7 years, 7 months

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[Linux-stable-mirror] FAILED: patch "[PATCH] sched/rt: Simplify the IPI based RT balancing logic" failed to apply to 3.18-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 3.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 4bdced5c9a2922521e325896a7bbbf0132c94e56 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" <rostedt(a)goodmis.org> Date: Fri, 6 Oct 2017 14:05:04 -0400 Subject: [PATCH] sched/rt: Simplify the IPI based RT balancing logic When a CPU lowers its priority (schedules out a high priority task for a lower priority one), a check is made to see if any other CPU has overloaded RT tasks (more than one). It checks the rto_mask to determine this and if so it will request to pull one of those tasks to itself if the non running RT task is of higher priority than the new priority of the next task to run on the current CPU. When we deal with large number of CPUs, the original pull logic suffered from large lock contention on a single CPU run queue, which caused a huge latency across all CPUs. This was caused by only having one CPU having overloaded RT tasks and a bunch of other CPUs lowering their priority. To solve this issue, commit: b6366f048e0c ("sched/rt: Use IPI to trigger RT task push migration instead of pulling") changed the way to request a pull. Instead of grabbing the lock of the overloaded CPU's runqueue, it simply sent an IPI to that CPU to do the work. Although the IPI logic worked very well in removing the large latency build up, it still could suffer from a large number of IPIs being sent to a single CPU. On a 80 CPU box, I measured over 200us of processing IPIs. Worse yet, when I tested this on a 120 CPU box, with a stress test that had lots of RT tasks scheduling on all CPUs, it actually triggered the hard lockup detector! One CPU had so many IPIs sent to it, and due to the restart mechanism that is triggered when the source run queue has a priority status change, the CPU spent minutes! processing the IPIs. Thinking about this further, I realized there's no reason for each run queue to send its own IPI. As all CPUs with overloaded tasks must be scanned regardless if there's one or many CPUs lowering their priority, because there's no current way to find the CPU with the highest priority task that can schedule to one of these CPUs, there really only needs to be one IPI being sent around at a time. This greatly simplifies the code! The new approach is to have each root domain have its own irq work, as the rto_mask is per root domain. The root domain has the following fields attached to it: rto_push_work - the irq work to process each CPU set in rto_mask rto_lock - the lock to protect some of the other rto fields rto_loop_start - an atomic that keeps contention down on rto_lock the first CPU scheduling in a lower priority task is the one to kick off the process. rto_loop_next - an atomic that gets incremented for each CPU that schedules in a lower priority task. rto_loop - a variable protected by rto_lock that is used to compare against rto_loop_next rto_cpu - The cpu to send the next IPI to, also protected by the rto_lock. When a CPU schedules in a lower priority task and wants to make sure overloaded CPUs know about it. It increments the rto_loop_next. Then it atomically sets rto_loop_start with a cmpxchg. If the old value is not "0", then it is done, as another CPU is kicking off the IPI loop. If the old value is "0", then it will take the rto_lock to synchronize with a possible IPI being sent around to the overloaded CPUs. If rto_cpu is greater than or equal to nr_cpu_ids, then there's either no IPI being sent around, or one is about to finish. Then rto_cpu is set to the first CPU in rto_mask and an IPI is sent to that CPU. If there's no CPUs set in rto_mask, then there's nothing to be done. When the CPU receives the IPI, it will first try to push any RT tasks that is queued on the CPU but can't run because a higher priority RT task is currently running on that CPU. Then it takes the rto_lock and looks for the next CPU in the rto_mask. If it finds one, it simply sends an IPI to that CPU and the process continues. If there's no more CPUs in the rto_mask, then rto_loop is compared with rto_loop_next. If they match, everything is done and the process is over. If they do not match, then a CPU scheduled in a lower priority task as the IPI was being passed around, and the process needs to start again. The first CPU in rto_mask is sent the IPI. This change removes this duplication of work in the IPI logic, and greatly lowers the latency caused by the IPIs. This removed the lockup happening on the 120 CPU machine. It also simplifies the code tremendously. What else could anyone ask for? Thanks to Peter Zijlstra for simplifying the rto_loop_start atomic logic and supplying me with the rto_start_trylock() and rto_start_unlock() helper functions. Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Cc: Clark Williams <williams(a)redhat.com> Cc: Daniel Bristot de Oliveira <bristot(a)redhat.com> Cc: John Kacur <jkacur(a)redhat.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Mike Galbraith <efault(a)gmx.de> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Scott Wood <swood(a)redhat.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Link: http://lkml.kernel.org/r/20170424114732.1aac6dc4@gandalf.local.home Signed-off-by: Ingo Molnar <mingo(a)kernel.org> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 0af5ca9e3e3f..fda27991699a 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -73,10 +73,6 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b) raw_spin_unlock(&rt_b->rt_runtime_lock); } -#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI) -static void push_irq_work_func(struct irq_work *work); -#endif - void init_rt_rq(struct rt_rq *rt_rq) { struct rt_prio_array *array; @@ -96,13 +92,6 @@ void init_rt_rq(struct rt_rq *rt_rq) rt_rq->rt_nr_migratory = 0; rt_rq->overloaded = 0; plist_head_init(&rt_rq->pushable_tasks); - -#ifdef HAVE_RT_PUSH_IPI - rt_rq->push_flags = 0; - rt_rq->push_cpu = nr_cpu_ids; - raw_spin_lock_init(&rt_rq->push_lock); - init_irq_work(&rt_rq->push_work, push_irq_work_func); -#endif #endif /* CONFIG_SMP */ /* We start is dequeued state, because no RT tasks are queued */ rt_rq->rt_queued = 0; @@ -1875,241 +1864,166 @@ static void push_rt_tasks(struct rq *rq) } #ifdef HAVE_RT_PUSH_IPI + /* - * The search for the next cpu always starts at rq->cpu and ends - * when we reach rq->cpu again. It will never return rq->cpu. - * This returns the next cpu to check, or nr_cpu_ids if the loop - * is complete. + * When a high priority task schedules out from a CPU and a lower priority + * task is scheduled in, a check is made to see if there's any RT tasks + * on other CPUs that are waiting to run because a higher priority RT task + * is currently running on its CPU. In this case, the CPU with multiple RT + * tasks queued on it (overloaded) needs to be notified that a CPU has opened + * up that may be able to run one of its non-running queued RT tasks. + * + * All CPUs with overloaded RT tasks need to be notified as there is currently + * no way to know which of these CPUs have the highest priority task waiting + * to run. Instead of trying to take a spinlock on each of these CPUs, + * which has shown to cause large latency when done on machines with many + * CPUs, sending an IPI to the CPUs to have them push off the overloaded + * RT tasks waiting to run. + * + * Just sending an IPI to each of the CPUs is also an issue, as on large + * count CPU machines, this can cause an IPI storm on a CPU, especially + * if its the only CPU with multiple RT tasks queued, and a large number + * of CPUs scheduling a lower priority task at the same time. + * + * Each root domain has its own irq work function that can iterate over + * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT + * tassk must be checked if there's one or many CPUs that are lowering + * their priority, there's a single irq work iterator that will try to + * push off RT tasks that are waiting to run. + * + * When a CPU schedules a lower priority task, it will kick off the + * irq work iterator that will jump to each CPU with overloaded RT tasks. + * As it only takes the first CPU that schedules a lower priority task + * to start the process, the rto_start variable is incremented and if + * the atomic result is one, then that CPU will try to take the rto_lock. + * This prevents high contention on the lock as the process handles all + * CPUs scheduling lower priority tasks. + * + * All CPUs that are scheduling a lower priority task will increment the + * rt_loop_next variable. This will make sure that the irq work iterator + * checks all RT overloaded CPUs whenever a CPU schedules a new lower + * priority task, even if the iterator is in the middle of a scan. Incrementing + * the rt_loop_next will cause the iterator to perform another scan. * - * rq->rt.push_cpu holds the last cpu returned by this function, - * or if this is the first instance, it must hold rq->cpu. */ static int rto_next_cpu(struct rq *rq) { - int prev_cpu = rq->rt.push_cpu; + struct root_domain *rd = rq->rd; + int next; int cpu; - cpu = cpumask_next(prev_cpu, rq->rd->rto_mask); - /* - * If the previous cpu is less than the rq's CPU, then it already - * passed the end of the mask, and has started from the beginning. - * We end if the next CPU is greater or equal to rq's CPU. + * When starting the IPI RT pushing, the rto_cpu is set to -1, + * rt_next_cpu() will simply return the first CPU found in + * the rto_mask. + * + * If rto_next_cpu() is called with rto_cpu is a valid cpu, it + * will return the next CPU found in the rto_mask. + * + * If there are no more CPUs left in the rto_mask, then a check is made + * against rto_loop and rto_loop_next. rto_loop is only updated with + * the rto_lock held, but any CPU may increment the rto_loop_next + * without any locking. */ - if (prev_cpu < rq->cpu) { - if (cpu >= rq->cpu) - return nr_cpu_ids; + for (;;) { - } else if (cpu >= nr_cpu_ids) { - /* - * We passed the end of the mask, start at the beginning. - * If the result is greater or equal to the rq's CPU, then - * the loop is finished. - */ - cpu = cpumask_first(rq->rd->rto_mask); - if (cpu >= rq->cpu) - return nr_cpu_ids; - } - rq->rt.push_cpu = cpu; + /* When rto_cpu is -1 this acts like cpumask_first() */ + cpu = cpumask_next(rd->rto_cpu, rd->rto_mask); - /* Return cpu to let the caller know if the loop is finished or not */ - return cpu; -} + rd->rto_cpu = cpu; -static int find_next_push_cpu(struct rq *rq) -{ - struct rq *next_rq; - int cpu; + if (cpu < nr_cpu_ids) + return cpu; - while (1) { - cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - break; - next_rq = cpu_rq(cpu); + rd->rto_cpu = -1; + + /* + * ACQUIRE ensures we see the @rto_mask changes + * made prior to the @next value observed. + * + * Matches WMB in rt_set_overload(). + */ + next = atomic_read_acquire(&rd->rto_loop_next); - /* Make sure the next rq can push to this rq */ - if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr) + if (rd->rto_loop == next) break; + + rd->rto_loop = next; } - return cpu; + return -1; } -#define RT_PUSH_IPI_EXECUTING 1 -#define RT_PUSH_IPI_RESTART 2 +static inline bool rto_start_trylock(atomic_t *v) +{ + return !atomic_cmpxchg_acquire(v, 0, 1); +} -/* - * When a high priority task schedules out from a CPU and a lower priority - * task is scheduled in, a check is made to see if there's any RT tasks - * on other CPUs that are waiting to run because a higher priority RT task - * is currently running on its CPU. In this case, the CPU with multiple RT - * tasks queued on it (overloaded) needs to be notified that a CPU has opened - * up that may be able to run one of its non-running queued RT tasks. - * - * On large CPU boxes, there's the case that several CPUs could schedule - * a lower priority task at the same time, in which case it will look for - * any overloaded CPUs that it could pull a task from. To do this, the runqueue - * lock must be taken from that overloaded CPU. Having 10s of CPUs all fighting - * for a single overloaded CPU's runqueue lock can produce a large latency. - * (This has actually been observed on large boxes running cyclictest). - * Instead of taking the runqueue lock of the overloaded CPU, each of the - * CPUs that scheduled a lower priority task simply sends an IPI to the - * overloaded CPU. An IPI is much cheaper than taking an runqueue lock with - * lots of contention. The overloaded CPU will look to push its non-running - * RT task off, and if it does, it can then ignore the other IPIs coming - * in, and just pass those IPIs off to any other overloaded CPU. - * - * When a CPU schedules a lower priority task, it only sends an IPI to - * the "next" CPU that has overloaded RT tasks. This prevents IPI storms, - * as having 10 CPUs scheduling lower priority tasks and 10 CPUs with - * RT overloaded tasks, would cause 100 IPIs to go out at once. - * - * The overloaded RT CPU, when receiving an IPI, will try to push off its - * overloaded RT tasks and then send an IPI to the next CPU that has - * overloaded RT tasks. This stops when all CPUs with overloaded RT tasks - * have completed. Just because a CPU may have pushed off its own overloaded - * RT task does not mean it should stop sending the IPI around to other - * overloaded CPUs. There may be another RT task waiting to run on one of - * those CPUs that are of higher priority than the one that was just - * pushed. - * - * An optimization that could possibly be made is to make a CPU array similar - * to the cpupri array mask of all running RT tasks, but for the overloaded - * case, then the IPI could be sent to only the CPU with the highest priority - * RT task waiting, and that CPU could send off further IPIs to the CPU with - * the next highest waiting task. Since the overloaded case is much less likely - * to happen, the complexity of this implementation may not be worth it. - * Instead, just send an IPI around to all overloaded CPUs. - * - * The rq->rt.push_flags holds the status of the IPI that is going around. - * A run queue can only send out a single IPI at a time. The possible flags - * for rq->rt.push_flags are: - * - * (None or zero): No IPI is going around for the current rq - * RT_PUSH_IPI_EXECUTING: An IPI for the rq is being passed around - * RT_PUSH_IPI_RESTART: The priority of the running task for the rq - * has changed, and the IPI should restart - * circulating the overloaded CPUs again. - * - * rq->rt.push_cpu contains the CPU that is being sent the IPI. It is updated - * before sending to the next CPU. - * - * Instead of having all CPUs that schedule a lower priority task send - * an IPI to the same "first" CPU in the RT overload mask, they send it - * to the next overloaded CPU after their own CPU. This helps distribute - * the work when there's more than one overloaded CPU and multiple CPUs - * scheduling in lower priority tasks. - * - * When a rq schedules a lower priority task than what was currently - * running, the next CPU with overloaded RT tasks is examined first. - * That is, if CPU 1 and 5 are overloaded, and CPU 3 schedules a lower - * priority task, it will send an IPI first to CPU 5, then CPU 5 will - * send to CPU 1 if it is still overloaded. CPU 1 will clear the - * rq->rt.push_flags if RT_PUSH_IPI_RESTART is not set. - * - * The first CPU to notice IPI_RESTART is set, will clear that flag and then - * send an IPI to the next overloaded CPU after the rq->cpu and not the next - * CPU after push_cpu. That is, if CPU 1, 4 and 5 are overloaded when CPU 3 - * schedules a lower priority task, and the IPI_RESTART gets set while the - * handling is being done on CPU 5, it will clear the flag and send it back to - * CPU 4 instead of CPU 1. - * - * Note, the above logic can be disabled by turning off the sched_feature - * RT_PUSH_IPI. Then the rq lock of the overloaded CPU will simply be - * taken by the CPU requesting a pull and the waiting RT task will be pulled - * by that CPU. This may be fine for machines with few CPUs. - */ -static void tell_cpu_to_push(struct rq *rq) +static inline void rto_start_unlock(atomic_t *v) { - int cpu; + atomic_set_release(v, 0); +} - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - raw_spin_lock(&rq->rt.push_lock); - /* Make sure it's still executing */ - if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { - /* - * Tell the IPI to restart the loop as things have - * changed since it started. - */ - rq->rt.push_flags |= RT_PUSH_IPI_RESTART; - raw_spin_unlock(&rq->rt.push_lock); - return; - } - raw_spin_unlock(&rq->rt.push_lock); - } +static void tell_cpu_to_push(struct rq *rq) +{ + int cpu = -1; - /* When here, there's no IPI going around */ + /* Keep the loop going if the IPI is currently active */ + atomic_inc(&rq->rd->rto_loop_next); - rq->rt.push_cpu = rq->cpu; - cpu = find_next_push_cpu(rq); - if (cpu >= nr_cpu_ids) + /* Only one CPU can initiate a loop at a time */ + if (!rto_start_trylock(&rq->rd->rto_loop_start)) return; - rq->rt.push_flags = RT_PUSH_IPI_EXECUTING; + raw_spin_lock(&rq->rd->rto_lock); + + /* + * The rto_cpu is updated under the lock, if it has a valid cpu + * then the IPI is still running and will continue due to the + * update to loop_next, and nothing needs to be done here. + * Otherwise it is finishing up and an ipi needs to be sent. + */ + if (rq->rd->rto_cpu < 0) + cpu = rto_next_cpu(rq); - irq_work_queue_on(&rq->rt.push_work, cpu); + raw_spin_unlock(&rq->rd->rto_lock); + + rto_start_unlock(&rq->rd->rto_loop_start); + + if (cpu >= 0) + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } /* Called from hardirq context */ -static void try_to_push_tasks(void *arg) +void rto_push_irq_work_func(struct irq_work *work) { - struct rt_rq *rt_rq = arg; - struct rq *rq, *src_rq; - int this_cpu; + struct rq *rq; int cpu; - this_cpu = rt_rq->push_cpu; + rq = this_rq(); - /* Paranoid check */ - BUG_ON(this_cpu != smp_processor_id()); - - rq = cpu_rq(this_cpu); - src_rq = rq_of_rt_rq(rt_rq); - -again: + /* + * We do not need to grab the lock to check for has_pushable_tasks. + * When it gets updated, a check is made if a push is possible. + */ if (has_pushable_tasks(rq)) { raw_spin_lock(&rq->lock); - push_rt_task(rq); + push_rt_tasks(rq); raw_spin_unlock(&rq->lock); } - /* Pass the IPI to the next rt overloaded queue */ - raw_spin_lock(&rt_rq->push_lock); - /* - * If the source queue changed since the IPI went out, - * we need to restart the search from that CPU again. - */ - if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) { - rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART; - rt_rq->push_cpu = src_rq->cpu; - } + raw_spin_lock(&rq->rd->rto_lock); - cpu = find_next_push_cpu(src_rq); + /* Pass the IPI to the next rt overloaded queue */ + cpu = rto_next_cpu(rq); - if (cpu >= nr_cpu_ids) - rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING; - raw_spin_unlock(&rt_rq->push_lock); + raw_spin_unlock(&rq->rd->rto_lock); - if (cpu >= nr_cpu_ids) + if (cpu < 0) return; - /* - * It is possible that a restart caused this CPU to be - * chosen again. Don't bother with an IPI, just see if we - * have more to push. - */ - if (unlikely(cpu == rq->cpu)) - goto again; - /* Try the next RT overloaded CPU */ - irq_work_queue_on(&rt_rq->push_work, cpu); -} - -static void push_irq_work_func(struct irq_work *work) -{ - struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work); - - try_to_push_tasks(rt_rq); + irq_work_queue_on(&rq->rd->rto_push_work, cpu); } #endif /* HAVE_RT_PUSH_IPI */ diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a81c9782e98c..8aa24b41f652 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -505,7 +505,7 @@ static inline int rt_bandwidth_enabled(void) } /* RT IPI pull logic requires IRQ_WORK */ -#ifdef CONFIG_IRQ_WORK +#if defined(CONFIG_IRQ_WORK) && defined(CONFIG_SMP) # define HAVE_RT_PUSH_IPI #endif @@ -527,12 +527,6 @@ struct rt_rq { unsigned long rt_nr_total; int overloaded; struct plist_head pushable_tasks; -#ifdef HAVE_RT_PUSH_IPI - int push_flags; - int push_cpu; - struct irq_work push_work; - raw_spinlock_t push_lock; -#endif #endif /* CONFIG_SMP */ int rt_queued; @@ -641,6 +635,19 @@ struct root_domain { struct dl_bw dl_bw; struct cpudl cpudl; +#ifdef HAVE_RT_PUSH_IPI + /* + * For IPI pull requests, loop across the rto_mask. + */ + struct irq_work rto_push_work; + raw_spinlock_t rto_lock; + /* These are only updated and read within rto_lock */ + int rto_loop; + int rto_cpu; + /* These atomics are updated outside of a lock */ + atomic_t rto_loop_next; + atomic_t rto_loop_start; +#endif /* * The "RT overload" flag: it gets set if a CPU has more than * one runnable RT task. @@ -658,6 +665,9 @@ extern void init_defrootdomain(void); extern int sched_init_domains(const struct cpumask *cpu_map); extern void rq_attach_root(struct rq *rq, struct root_domain *rd); +#ifdef HAVE_RT_PUSH_IPI +extern void rto_push_irq_work_func(struct irq_work *work); +#endif #endif /* CONFIG_SMP */ /* diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index f51d123f9fe1..e50450c2fed8 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -268,6 +268,12 @@ static int init_rootdomain(struct root_domain *rd) if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) goto free_dlo_mask; +#ifdef HAVE_RT_PUSH_IPI + rd->rto_cpu = -1; + raw_spin_lock_init(&rd->rto_lock); + init_irq_work(&rd->rto_push_work, rto_push_irq_work_func); +#endif + init_dl_bw(&rd->dl_bw); if (cpudl_init(&rd->cpudl) != 0) goto free_rto_mask;

7 years, 7 months

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[Linux-stable-mirror] [PATCH v2] sunxi-rsb: Include OF based modalias in device uevent

by Stefan Brüns

Include the OF-based modalias in the uevent sent when registering devices on the sunxi RSB bus, so that user space has a chance to autoload the kernel module for the device. Fixes a regression caused by commit 3f241bfa60bd ("arm64: allwinner: a64: pine64: Use dcdc1 regulator for mmc0"). When the axp20x-rsb module for the AXP803 PMIC is built as a module, it is not loaded and the system ends up with an disfunctional MMC controller. Cc: stable <stable(a)vger.kernel.org> Signed-off-by: Stefan Brüns <stefan.bruens(a)rwth-aachen.de> --- drivers/bus/sunxi-rsb.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c index 328ca93781cf..1b76d9585902 100644 --- a/drivers/bus/sunxi-rsb.c +++ b/drivers/bus/sunxi-rsb.c @@ -178,6 +178,7 @@ static struct bus_type sunxi_rsb_bus = { .match = sunxi_rsb_device_match, .probe = sunxi_rsb_device_probe, .remove = sunxi_rsb_device_remove, + .uevent = of_device_uevent_modalias, }; static void sunxi_rsb_dev_release(struct device *dev) -- 2.15.0

7 years, 7 months

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[Linux-stable-mirror] Applied "spi: a3700: Fix clk prescaling for coefficient over 15" to the spi tree

by Mark Brown

The patch spi: a3700: Fix clk prescaling for coefficient over 15 has been applied to the spi tree at https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark >From 251c201bf4f8b5bf4f1ccb4f8920eed2e1f57580 Mon Sep 17 00:00:00 2001 From: Maxime Chevallier <maxime.chevallier(a)smile.fr> Date: Mon, 27 Nov 2017 15:16:32 +0100 Subject: [PATCH] spi: a3700: Fix clk prescaling for coefficient over 15 The Armada 3700 SPI controller has 2 ranges of prescaler coefficients. One ranging from 0 to 15 by steps of 1, and one ranging from 0 to 30 by steps of 2. This commit fixes the prescaler coefficients that are over 15 so that it uses the correct range of values. The prescaling coefficient is rounded to the upper value if it is odd. This was tested on Espressobin with spidev and a locigal analyser. Signed-off-by: Maxime Chevallier <maxime.chevallier(a)smile.fr> Signed-off-by: Mark Brown <broonie(a)kernel.org> Cc: stable(a)vger.kernel.org --- drivers/spi/spi-armada-3700.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/spi/spi-armada-3700.c b/drivers/spi/spi-armada-3700.c index 77fe55ce790c..d65345312527 100644 --- a/drivers/spi/spi-armada-3700.c +++ b/drivers/spi/spi-armada-3700.c @@ -79,6 +79,7 @@ #define A3700_SPI_BYTE_LEN BIT(5) #define A3700_SPI_CLK_PRESCALE BIT(0) #define A3700_SPI_CLK_PRESCALE_MASK (0x1f) +#define A3700_SPI_CLK_EVEN_OFFS (0x10) #define A3700_SPI_WFIFO_THRS_BIT 28 #define A3700_SPI_RFIFO_THRS_BIT 24 @@ -220,6 +221,13 @@ static void a3700_spi_clock_set(struct a3700_spi *a3700_spi, prescale = DIV_ROUND_UP(clk_get_rate(a3700_spi->clk), speed_hz); + /* For prescaler values over 15, we can only set it by steps of 2. + * Starting from A3700_SPI_CLK_EVEN_OFFS, we set values from 0 up to + * 30. We only use this range from 16 to 30. + */ + if (prescale > 15) + prescale = A3700_SPI_CLK_EVEN_OFFS + DIV_ROUND_UP(prescale, 2); + val = spireg_read(a3700_spi, A3700_SPI_IF_CFG_REG); val = val & ~A3700_SPI_CLK_PRESCALE_MASK; -- 2.15.0

7 years, 7 months

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Re: [Linux-stable-mirror] [PATCH] sunxi-rsb: Include OF based modalias in device uevent

by Chen-Yu Tsai

On Tue, Nov 28, 2017 at 1:19 AM, Stefan Brüns <stefan.bruens(a)rwth-aachen.de> wrote: > On Monday, November 27, 2017 4:35:02 PM CET Maxime Ripard wrote: >> Hi, >> >> On Mon, Nov 27, 2017 at 01:17:25PM +0100, Stefan Brüns wrote: >> > Include the OF-based modalias in the uevent sent when registering devices >> > on the sunxi RSB bus, so that user space has a chance to autoload the >> > kernel module for the device. >> > >> > Fixes a regression caused by commit 3f241bfa60bd ("arm64: allwinner: a64: >> > pine64: Use dcdc1 regulator for mmc0"). When the axp20x-rsb module for >> > the AXP803 PMIC is built as a module, it is not loaded and the system >> > ends up with an disfunctional MMC controller. >> > >> > Cc: stable <stable(a)vger.kernel.org> >> > Signed-off-by: Stefan Brüns <stefan.bruens(a)rwth-aachen.de> >> > --- >> > >> > drivers/bus/sunxi-rsb.c | 13 +++++++++++++ >> > 1 file changed, 13 insertions(+) >> > >> > diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c >> > index 328ca93781cf..37cb57244cbe 100644 >> > --- a/drivers/bus/sunxi-rsb.c >> > +++ b/drivers/bus/sunxi-rsb.c >> > @@ -173,11 +173,24 @@ static int sunxi_rsb_device_remove(struct device >> > *dev)> >> > return drv->remove(to_sunxi_rsb_device(dev)); >> > >> > } >> > >> > +static int sunxi_rsb_device_uevent(struct device *dev, >> > + struct kobj_uevent_env *env) >> > +{ >> > + int ret; >> > + >> > + ret = of_device_uevent_modalias(dev, env); >> > + if (ret != -ENODEV) >> > + return ret; >> >> A comment explaining why we need to ignore the ENODEV error code would >> be great here. > > Lazy answer - everyone else is doing the same, and nobody cared to add an > explanation. > > For *some* drivers, this is likely because the same device may be enumerated > from e.g ACPI or OF, and for an ACPI device -ENODEV will be returned, as > dev->of_node is NULL. > > For devices which are only usable in an OF context, this is bogus. Not sure > about sunxi-rsb. sunxi-rsb (and Allwinner support in mainline in general) is OF only. With the exception of mfd sub-devices, if someone is enumerating devices in some other fashion, it should rightly blow up in their face. >> > + return 0; >> > +} >> > + >> > >> > static struct bus_type sunxi_rsb_bus = { >> > >> > .name = RSB_CTRL_NAME, >> > .match = sunxi_rsb_device_match, >> > .probe = sunxi_rsb_device_probe, >> > .remove = sunxi_rsb_device_remove, >> > >> > + .uevent = sunxi_rsb_device_uevent, >> >> Any reason to not use of_device_uevent_modalias directly here? > > *If* sunxi-rsb can be used without OF, then yes, otherwise no. You can just use of_device_uevent_modalias, like the other OF platforms. ChenYu

7 years, 7 months

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[Linux-stable-mirror] Patch "powerpc/signal: Properly handle return value from uprobe_deny_signal()" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled powerpc/signal: Properly handle return value from uprobe_deny_signal() to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: powerpc-signal-properly-handle-return-value-from-uprobe_deny_signal.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 46725b17f1c6c815a41429259b3f070c01e71bc1 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" <naveen.n.rao(a)linux.vnet.ibm.com> Date: Thu, 31 Aug 2017 21:55:57 +0530 Subject: powerpc/signal: Properly handle return value from uprobe_deny_signal() From: Naveen N. Rao <naveen.n.rao(a)linux.vnet.ibm.com> commit 46725b17f1c6c815a41429259b3f070c01e71bc1 upstream. When a uprobe is installed on an instruction that we currently do not emulate, we copy the instruction into a xol buffer and single step that instruction. If that instruction generates a fault, we abort the single stepping before invoking the signal handler. Once the signal handler is done, the uprobe trap is hit again since the instruction is retried and the process repeats. We use uprobe_deny_signal() to detect if the xol instruction triggered a signal. If so, we clear TIF_SIGPENDING and set TIF_UPROBE so that the signal is not handled until after the single stepping is aborted. In this case, uprobe_deny_signal() returns true and get_signal() ends up returning 0. However, in do_signal(), we are not looking at the return value, but depending on ksig.sig for further action, all with an uninitialized ksig that is not touched in this scenario. Fix the same by initializing ksig.sig to 0. Fixes: 129b69df9c90 ("powerpc: Use get_signal() signal_setup_done()") Reported-by: Anton Blanchard <anton(a)samba.org> Signed-off-by: Naveen N. Rao <naveen.n.rao(a)linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- arch/powerpc/kernel/signal.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/powerpc/kernel/signal.c +++ b/arch/powerpc/kernel/signal.c @@ -102,7 +102,7 @@ static void check_syscall_restart(struct static void do_signal(struct task_struct *tsk) { sigset_t *oldset = sigmask_to_save(); - struct ksignal ksig; + struct ksignal ksig = { .sig = 0 }; int ret; int is32 = is_32bit_task(); Patches currently in stable-queue which might be from naveen.n.rao(a)linux.vnet.ibm.com are queue-4.9/powerpc-signal-properly-handle-return-value-from-uprobe_deny_signal.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "parisc: Fix validity check of pointer size argument in new CAS implementation" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled parisc: Fix validity check of pointer size argument in new CAS implementation to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: parisc-fix-validity-check-of-pointer-size-argument-in-new-cas-implementation.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 05f016d2ca7a4fab99d5d5472168506ddf95e74f Mon Sep 17 00:00:00 2001 From: John David Anglin <dave.anglin(a)bell.net> Date: Sat, 11 Nov 2017 17:11:16 -0500 Subject: parisc: Fix validity check of pointer size argument in new CAS implementation From: John David Anglin <dave.anglin(a)bell.net> commit 05f016d2ca7a4fab99d5d5472168506ddf95e74f upstream. As noted by Christoph Biedl, passing a pointer size of 4 in the new CAS implementation causes a kernel crash. The attached patch corrects the off by one error in the argument validity check. In reviewing the code, I noticed that we only perform word operations with the pointer size argument. The subi instruction intentionally uses a word condition on 64-bit kernels. Nullification was used instead of a cmpib instruction as the branch should never be taken. The shlw pseudo-operation generates a depw,z instruction and it clears the target before doing a shift left word deposit. Thus, we don't need to clip the upper 32 bits of this argument on 64-bit kernels. Tested with a gcc testsuite run with a 64-bit kernel. The gcc atomic code in libgcc is the only direct user of the new CAS implementation that I am aware of. Signed-off-by: John David Anglin <dave.anglin(a)bell.net> Signed-off-by: Helge Deller <deller(a)gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- arch/parisc/kernel/syscall.S | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/arch/parisc/kernel/syscall.S +++ b/arch/parisc/kernel/syscall.S @@ -690,15 +690,15 @@ cas_action: /* ELF32 Process entry path */ lws_compare_and_swap_2: #ifdef CONFIG_64BIT - /* Clip the input registers */ + /* Clip the input registers. We don't need to clip %r23 as we + only use it for word operations */ depdi 0, 31, 32, %r26 depdi 0, 31, 32, %r25 depdi 0, 31, 32, %r24 - depdi 0, 31, 32, %r23 #endif /* Check the validity of the size pointer */ - subi,>>= 4, %r23, %r0 + subi,>>= 3, %r23, %r0 b,n lws_exit_nosys /* Jump to the functions which will load the old and new values into Patches currently in stable-queue which might be from dave.anglin(a)bell.net are queue-4.9/parisc-fix-validity-check-of-pointer-size-argument-in-new-cas-implementation.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "media: v4l2-ctrl: Fix flags field on Control events" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled media: v4l2-ctrl: Fix flags field on Control events to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: media-v4l2-ctrl-fix-flags-field-on-control-events.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 9cac9d2fb2fe0e0cadacdb94415b3fe49e3f724f Mon Sep 17 00:00:00 2001 From: Ricardo Ribalda <ricardo.ribalda(a)gmail.com> Date: Tue, 17 Oct 2017 11:48:50 -0400 Subject: media: v4l2-ctrl: Fix flags field on Control events From: Ricardo Ribalda Delgado <ricardo.ribalda(a)gmail.com> commit 9cac9d2fb2fe0e0cadacdb94415b3fe49e3f724f upstream. VIDIOC_DQEVENT and VIDIOC_QUERY_EXT_CTRL should give the same output for the control flags field. This patch creates a new function user_flags(), that calculates the user exported flags value (which is different than the kernel internal flags structure). This function is then used by all the code that exports the internal flags to userspace. Reported-by: Dimitrios Katsaros <patcherwork(a)gmail.com> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda(a)gmail.com> Signed-off-by: Hans Verkuil <hans.verkuil(a)cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab(a)s-opensource.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/media/v4l2-core/v4l2-ctrls.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) --- a/drivers/media/v4l2-core/v4l2-ctrls.c +++ b/drivers/media/v4l2-core/v4l2-ctrls.c @@ -1219,6 +1219,16 @@ void v4l2_ctrl_fill(u32 id, const char * } EXPORT_SYMBOL(v4l2_ctrl_fill); +static u32 user_flags(const struct v4l2_ctrl *ctrl) +{ + u32 flags = ctrl->flags; + + if (ctrl->is_ptr) + flags |= V4L2_CTRL_FLAG_HAS_PAYLOAD; + + return flags; +} + static void fill_event(struct v4l2_event *ev, struct v4l2_ctrl *ctrl, u32 changes) { memset(ev->reserved, 0, sizeof(ev->reserved)); @@ -1226,7 +1236,7 @@ static void fill_event(struct v4l2_event ev->id = ctrl->id; ev->u.ctrl.changes = changes; ev->u.ctrl.type = ctrl->type; - ev->u.ctrl.flags = ctrl->flags; + ev->u.ctrl.flags = user_flags(ctrl); if (ctrl->is_ptr) ev->u.ctrl.value64 = 0; else @@ -2550,10 +2560,8 @@ int v4l2_query_ext_ctrl(struct v4l2_ctrl else qc->id = ctrl->id; strlcpy(qc->name, ctrl->name, sizeof(qc->name)); - qc->flags = ctrl->flags; + qc->flags = user_flags(ctrl); qc->type = ctrl->type; - if (ctrl->is_ptr) - qc->flags |= V4L2_CTRL_FLAG_HAS_PAYLOAD; qc->elem_size = ctrl->elem_size; qc->elems = ctrl->elems; qc->nr_of_dims = ctrl->nr_of_dims; Patches currently in stable-queue which might be from ricardo.ribalda(a)gmail.com are queue-4.9/media-v4l2-ctrl-fix-flags-field-on-control-events.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "media: rc: check for integer overflow" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled media: rc: check for integer overflow to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: media-rc-check-for-integer-overflow.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 3e45067f94bbd61dec0619b1c32744eb0de480c8 Mon Sep 17 00:00:00 2001 From: Sean Young <sean(a)mess.org> Date: Sun, 8 Oct 2017 14:18:52 -0400 Subject: media: rc: check for integer overflow From: Sean Young <sean(a)mess.org> commit 3e45067f94bbd61dec0619b1c32744eb0de480c8 upstream. The ioctl LIRC_SET_REC_TIMEOUT would set a timeout of 704ns if called with a timeout of 4294968us. Signed-off-by: Sean Young <sean(a)mess.org> Signed-off-by: Mauro Carvalho Chehab <mchehab(a)s-opensource.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/media/rc/ir-lirc-codec.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/media/rc/ir-lirc-codec.c +++ b/drivers/media/rc/ir-lirc-codec.c @@ -286,11 +286,14 @@ static long ir_lirc_ioctl(struct file *f if (!dev->max_timeout) return -ENOSYS; + /* Check for multiply overflow */ + if (val > U32_MAX / 1000) + return -EINVAL; + tmp = val * 1000; - if (tmp < dev->min_timeout || - tmp > dev->max_timeout) - return -EINVAL; + if (tmp < dev->min_timeout || tmp > dev->max_timeout) + return -EINVAL; if (dev->s_timeout) ret = dev->s_timeout(dev, tmp); Patches currently in stable-queue which might be from sean(a)mess.org are queue-4.9/media-rc-check-for-integer-overflow.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "media: Don't do DMA on stack for firmware upload in the AS102 driver" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled media: Don't do DMA on stack for firmware upload in the AS102 driver to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: media-don-t-do-dma-on-stack-for-firmware-upload-in-the-as102-driver.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From b3120d2cc447ee77b9d69bf4ad7b452c9adb4d39 Mon Sep 17 00:00:00 2001 From: Michele Baldessari <michele(a)acksyn.org> Date: Mon, 6 Nov 2017 08:50:22 -0500 Subject: media: Don't do DMA on stack for firmware upload in the AS102 driver From: Michele Baldessari <michele(a)acksyn.org> commit b3120d2cc447ee77b9d69bf4ad7b452c9adb4d39 upstream. Firmware load on AS102 is using the stack which is not allowed any longer. We currently fail with: kernel: transfer buffer not dma capable kernel: ------------[ cut here ]------------ kernel: WARNING: CPU: 0 PID: 598 at drivers/usb/core/hcd.c:1595 usb_hcd_map_urb_for_dma+0x41d/0x620 kernel: Modules linked in: amd64_edac_mod(-) edac_mce_amd as102_fe dvb_as102(+) kvm_amd kvm snd_hda_codec_realtek dvb_core snd_hda_codec_generic snd_hda_codec_hdmi snd_hda_intel snd_hda_codec irqbypass crct10dif_pclmul crc32_pclmul snd_hda_core snd_hwdep snd_seq ghash_clmulni_intel sp5100_tco fam15h_power wmi k10temp i2c_piix4 snd_seq_device snd_pcm snd_timer parport_pc parport tpm_infineon snd tpm_tis soundcore tpm_tis_core tpm shpchp acpi_cpufreq xfs libcrc32c amdgpu amdkfd amd_iommu_v2 radeon hid_logitech_hidpp i2c_algo_bit drm_kms_helper crc32c_intel ttm drm r8169 mii hid_logitech_dj kernel: CPU: 0 PID: 598 Comm: systemd-udevd Not tainted 4.13.10-200.fc26.x86_64 #1 kernel: Hardware name: ASUS All Series/AM1I-A, BIOS 0505 03/13/2014 kernel: task: ffff979933b24c80 task.stack: ffffaf83413a4000 kernel: RIP: 0010:usb_hcd_map_urb_for_dma+0x41d/0x620 systemd-fsck[659]: /dev/sda2: clean, 49/128016 files, 268609/512000 blocks kernel: RSP: 0018:ffffaf83413a7728 EFLAGS: 00010282 systemd-udevd[604]: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable. kernel: RAX: 000000000000001f RBX: ffff979930bce780 RCX: 0000000000000000 kernel: RDX: 0000000000000000 RSI: ffff97993ec0e118 RDI: ffff97993ec0e118 kernel: RBP: ffffaf83413a7768 R08: 000000000000039a R09: 0000000000000000 kernel: R10: 0000000000000001 R11: 00000000ffffffff R12: 00000000fffffff5 kernel: R13: 0000000001400000 R14: 0000000000000001 R15: ffff979930806800 kernel: FS: 00007effaca5c8c0(0000) GS:ffff97993ec00000(0000) knlGS:0000000000000000 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 kernel: CR2: 00007effa9fca962 CR3: 0000000233089000 CR4: 00000000000406f0 kernel: Call Trace: kernel: usb_hcd_submit_urb+0x493/0xb40 kernel: ? page_cache_tree_insert+0x100/0x100 kernel: ? xfs_iunlock+0xd5/0x100 [xfs] kernel: ? xfs_file_buffered_aio_read+0x57/0xc0 [xfs] kernel: usb_submit_urb+0x22d/0x560 kernel: usb_start_wait_urb+0x6e/0x180 kernel: usb_bulk_msg+0xb8/0x160 kernel: as102_send_ep1+0x49/0xe0 [dvb_as102] kernel: ? devres_add+0x3f/0x50 kernel: as102_firmware_upload.isra.0+0x1dc/0x210 [dvb_as102] kernel: as102_fw_upload+0xb6/0x1f0 [dvb_as102] kernel: as102_dvb_register+0x2af/0x2d0 [dvb_as102] kernel: as102_usb_probe+0x1f3/0x260 [dvb_as102] kernel: usb_probe_interface+0x124/0x300 kernel: driver_probe_device+0x2ff/0x450 kernel: __driver_attach+0xa4/0xe0 kernel: ? driver_probe_device+0x450/0x450 kernel: bus_for_each_dev+0x6e/0xb0 kernel: driver_attach+0x1e/0x20 kernel: bus_add_driver+0x1c7/0x270 kernel: driver_register+0x60/0xe0 kernel: usb_register_driver+0x81/0x150 kernel: ? 0xffffffffc0807000 kernel: as102_usb_driver_init+0x1e/0x1000 [dvb_as102] kernel: do_one_initcall+0x50/0x190 kernel: ? __vunmap+0x81/0xb0 kernel: ? kfree+0x154/0x170 kernel: ? kmem_cache_alloc_trace+0x15f/0x1c0 kernel: ? do_init_module+0x27/0x1e9 kernel: do_init_module+0x5f/0x1e9 kernel: load_module+0x2602/0x2c30 kernel: SYSC_init_module+0x170/0x1a0 kernel: ? SYSC_init_module+0x170/0x1a0 kernel: SyS_init_module+0xe/0x10 kernel: do_syscall_64+0x67/0x140 kernel: entry_SYSCALL64_slow_path+0x25/0x25 kernel: RIP: 0033:0x7effab6cf3ea kernel: RSP: 002b:00007fff5cfcbbc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000af kernel: RAX: ffffffffffffffda RBX: 00005569e0b83760 RCX: 00007effab6cf3ea kernel: RDX: 00007effac2099c5 RSI: 0000000000009a13 RDI: 00005569e0b98c50 kernel: RBP: 00007effac2099c5 R08: 00005569e0b83ed0 R09: 0000000000001d80 kernel: R10: 00007effab98db00 R11: 0000000000000246 R12: 00005569e0b98c50 kernel: R13: 00005569e0b81c60 R14: 0000000000020000 R15: 00005569dfadfdf7 kernel: Code: 48 39 c8 73 30 80 3d 59 60 9d 00 00 41 bc f5 ff ff ff 0f 85 26 ff ff ff 48 c7 c7 b8 6b d0 92 c6 05 3f 60 9d 00 01 e8 24 3d ad ff <0f> ff 8b 53 64 e9 09 ff ff ff 65 48 8b 0c 25 00 d3 00 00 48 8b kernel: ---[ end trace c4cae366180e70ec ]--- kernel: as10x_usb: error during firmware upload part1 Let's allocate the the structure dynamically so we can get the firmware loaded correctly: [ 14.243057] as10x_usb: firmware: as102_data1_st.hex loaded with success [ 14.500777] as10x_usb: firmware: as102_data2_st.hex loaded with success Signed-off-by: Michele Baldessari <michele(a)acksyn.org> Signed-off-by: Mauro Carvalho Chehab <mchehab(a)s-opensource.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/media/usb/as102/as102_fw.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) --- a/drivers/media/usb/as102/as102_fw.c +++ b/drivers/media/usb/as102/as102_fw.c @@ -101,18 +101,23 @@ static int as102_firmware_upload(struct unsigned char *cmd, const struct firmware *firmware) { - struct as10x_fw_pkt_t fw_pkt; + struct as10x_fw_pkt_t *fw_pkt; int total_read_bytes = 0, errno = 0; unsigned char addr_has_changed = 0; + fw_pkt = kmalloc(sizeof(*fw_pkt), GFP_KERNEL); + if (!fw_pkt) + return -ENOMEM; + + for (total_read_bytes = 0; total_read_bytes < firmware->size; ) { int read_bytes = 0, data_len = 0; /* parse intel hex line */ read_bytes = parse_hex_line( (u8 *) (firmware->data + total_read_bytes), - fw_pkt.raw.address, - fw_pkt.raw.data, + fw_pkt->raw.address, + fw_pkt->raw.data, &data_len, &addr_has_changed); @@ -122,28 +127,28 @@ static int as102_firmware_upload(struct /* detect the end of file */ total_read_bytes += read_bytes; if (total_read_bytes == firmware->size) { - fw_pkt.u.request[0] = 0x00; - fw_pkt.u.request[1] = 0x03; + fw_pkt->u.request[0] = 0x00; + fw_pkt->u.request[1] = 0x03; /* send EOF command */ errno = bus_adap->ops->upload_fw_pkt(bus_adap, (uint8_t *) - &fw_pkt, 2, 0); + fw_pkt, 2, 0); if (errno < 0) goto error; } else { if (!addr_has_changed) { /* prepare command to send */ - fw_pkt.u.request[0] = 0x00; - fw_pkt.u.request[1] = 0x01; + fw_pkt->u.request[0] = 0x00; + fw_pkt->u.request[1] = 0x01; - data_len += sizeof(fw_pkt.u.request); - data_len += sizeof(fw_pkt.raw.address); + data_len += sizeof(fw_pkt->u.request); + data_len += sizeof(fw_pkt->raw.address); /* send cmd to device */ errno = bus_adap->ops->upload_fw_pkt(bus_adap, (uint8_t *) - &fw_pkt, + fw_pkt, data_len, 0); if (errno < 0) @@ -152,6 +157,7 @@ static int as102_firmware_upload(struct } } error: + kfree(fw_pkt); return (errno == 0) ? total_read_bytes : errno; } Patches currently in stable-queue which might be from michele(a)acksyn.org are queue-4.9/media-don-t-do-dma-on-stack-for-firmware-upload-in-the-as102-driver.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "ixgbe: Fix skb list corruption on Power systems" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled ixgbe: Fix skb list corruption on Power systems to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: ixgbe-fix-skb-list-corruption-on-power-systems.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 0a9a17e3bb4564caf4bfe2a6783ae1287667d188 Mon Sep 17 00:00:00 2001 From: Brian King <brking(a)linux.vnet.ibm.com> Date: Fri, 17 Nov 2017 11:05:43 -0600 Subject: ixgbe: Fix skb list corruption on Power systems From: Brian King <brking(a)linux.vnet.ibm.com> commit 0a9a17e3bb4564caf4bfe2a6783ae1287667d188 upstream. This patch fixes an issue seen on Power systems with ixgbe which results in skb list corruption and an eventual kernel oops. The following is what was observed: CPU 1 CPU2 ============================ ============================ 1: ixgbe_xmit_frame_ring ixgbe_clean_tx_irq 2: first->skb = skb eop_desc = tx_buffer->next_to_watch 3: ixgbe_tx_map read_barrier_depends() 4: wmb check adapter written status bit 5: first->next_to_watch = tx_desc napi_consume_skb(tx_buffer->skb ..); 6: writel(i, tx_ring->tail); The read_barrier_depends is insufficient to ensure that tx_buffer->skb does not get loaded prior to tx_buffer->next_to_watch, which then results in loading a stale skb pointer. This patch replaces the read_barrier_depends with smp_rmb to ensure loads are ordered with respect to the load of tx_buffer->next_to_watch. Signed-off-by: Brian King <brking(a)linux.vnet.ibm.com> Acked-by: Jesse Brandeburg <jesse.brandeburg(a)intel.com> Tested-by: Andrew Bowers <andrewx.bowers(a)intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher(a)intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -1171,7 +1171,7 @@ static bool ixgbe_clean_tx_irq(struct ix break; /* prevent any other reads prior to eop_desc */ - read_barrier_depends(); + smp_rmb(); /* if DD is not set pending work has not been completed */ if (!(eop_desc->wb.status & cpu_to_le32(IXGBE_TXD_STAT_DD))) Patches currently in stable-queue which might be from brking(a)linux.vnet.ibm.com are queue-4.9/i40evf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igb-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbevf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igbvf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/fm10k-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbe-fix-skb-list-corruption-on-power-systems.patch queue-4.9/i40e-use-smp_rmb-rather-than-read_barrier_depends.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "ixgbevf: Use smp_rmb rather than read_barrier_depends" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled ixgbevf: Use smp_rmb rather than read_barrier_depends to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: ixgbevf-use-smp_rmb-rather-than-read_barrier_depends.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From ae0c585d93dfaf923d2c7eb44b2c3ab92854ea9b Mon Sep 17 00:00:00 2001 From: Brian King <brking(a)linux.vnet.ibm.com> Date: Fri, 17 Nov 2017 11:05:45 -0600 Subject: ixgbevf: Use smp_rmb rather than read_barrier_depends From: Brian King <brking(a)linux.vnet.ibm.com> commit ae0c585d93dfaf923d2c7eb44b2c3ab92854ea9b upstream. The original issue being fixed in this patch was seen with the ixgbe driver, but the same issue exists with ixgbevf as well, as the code is very similar. read_barrier_depends is not sufficient to ensure loads following it are not speculatively loaded out of order by the CPU, which can result in stale data being loaded, causing potential system crashes. Signed-off-by: Brian King <brking(a)linux.vnet.ibm.com> Acked-by: Jesse Brandeburg <jesse.brandeburg(a)intel.com> Tested-by: Andrew Bowers <andrewx.bowers(a)intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher(a)intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c @@ -325,7 +325,7 @@ static bool ixgbevf_clean_tx_irq(struct break; /* prevent any other reads prior to eop_desc */ - read_barrier_depends(); + smp_rmb(); /* if DD is not set pending work has not been completed */ if (!(eop_desc->wb.status & cpu_to_le32(IXGBE_TXD_STAT_DD))) Patches currently in stable-queue which might be from brking(a)linux.vnet.ibm.com are queue-4.9/i40evf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igb-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbevf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igbvf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/fm10k-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbe-fix-skb-list-corruption-on-power-systems.patch queue-4.9/i40e-use-smp_rmb-rather-than-read_barrier_depends.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "igbvf: Use smp_rmb rather than read_barrier_depends" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled igbvf: Use smp_rmb rather than read_barrier_depends to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: igbvf-use-smp_rmb-rather-than-read_barrier_depends.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 1e1f9ca546556e508d021545861f6b5fc75a95fe Mon Sep 17 00:00:00 2001 From: Brian King <brking(a)linux.vnet.ibm.com> Date: Fri, 17 Nov 2017 11:05:46 -0600 Subject: igbvf: Use smp_rmb rather than read_barrier_depends From: Brian King <brking(a)linux.vnet.ibm.com> commit 1e1f9ca546556e508d021545861f6b5fc75a95fe upstream. The original issue being fixed in this patch was seen with the ixgbe driver, but the same issue exists with igbvf as well, as the code is very similar. read_barrier_depends is not sufficient to ensure loads following it are not speculatively loaded out of order by the CPU, which can result in stale data being loaded, causing potential system crashes. Signed-off-by: Brian King <brking(a)linux.vnet.ibm.com> Acked-by: Jesse Brandeburg <jesse.brandeburg(a)intel.com> Tested-by: Aaron Brown <aaron.f.brown(a)intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher(a)intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/net/ethernet/intel/igbvf/netdev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/net/ethernet/intel/igbvf/netdev.c +++ b/drivers/net/ethernet/intel/igbvf/netdev.c @@ -810,7 +810,7 @@ static bool igbvf_clean_tx_irq(struct ig break; /* prevent any other reads prior to eop_desc */ - read_barrier_depends(); + smp_rmb(); /* if DD is not set pending work has not been completed */ if (!(eop_desc->wb.status & cpu_to_le32(E1000_TXD_STAT_DD))) Patches currently in stable-queue which might be from brking(a)linux.vnet.ibm.com are queue-4.9/i40evf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igb-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbevf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igbvf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/fm10k-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbe-fix-skb-list-corruption-on-power-systems.patch queue-4.9/i40e-use-smp_rmb-rather-than-read_barrier_depends.patch

7 years, 7 months

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[Linux-stable-mirror] Patch "igb: Use smp_rmb rather than read_barrier_depends" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled igb: Use smp_rmb rather than read_barrier_depends to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: igb-use-smp_rmb-rather-than-read_barrier_depends.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From c4cb99185b4cc96c0a1c70104dc21ae14d7e7f28 Mon Sep 17 00:00:00 2001 From: Brian King <brking(a)linux.vnet.ibm.com> Date: Fri, 17 Nov 2017 11:05:47 -0600 Subject: igb: Use smp_rmb rather than read_barrier_depends From: Brian King <brking(a)linux.vnet.ibm.com> commit c4cb99185b4cc96c0a1c70104dc21ae14d7e7f28 upstream. The original issue being fixed in this patch was seen with the ixgbe driver, but the same issue exists with igb as well, as the code is very similar. read_barrier_depends is not sufficient to ensure loads following it are not speculatively loaded out of order by the CPU, which can result in stale data being loaded, causing potential system crashes. Signed-off-by: Brian King <brking(a)linux.vnet.ibm.com> Acked-by: Jesse Brandeburg <jesse.brandeburg(a)intel.com> Tested-by: Aaron Brown <aaron.f.brown(a)intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher(a)intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/net/ethernet/intel/igb/igb_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -6660,7 +6660,7 @@ static bool igb_clean_tx_irq(struct igb_ break; /* prevent any other reads prior to eop_desc */ - read_barrier_depends(); + smp_rmb(); /* if DD is not set pending work has not been completed */ if (!(eop_desc->wb.status & cpu_to_le32(E1000_TXD_STAT_DD))) Patches currently in stable-queue which might be from brking(a)linux.vnet.ibm.com are queue-4.9/i40evf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igb-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbevf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/igbvf-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/fm10k-use-smp_rmb-rather-than-read_barrier_depends.patch queue-4.9/ixgbe-fix-skb-list-corruption-on-power-systems.patch queue-4.9/i40e-use-smp_rmb-rather-than-read_barrier_depends.patch

7 years, 7 months

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