When a CFS task that was boosted by a SCHED_DEADLINE task boosts another CFS task (nested priority inheritance), Kernel panic is observed. Fixing priority inheritance changes the way how sched_deadline attributes are being inherited from original donor task.
Additional supporting patches are added to fix throttling of boosted tasks.
Daniel Bristot de Oliveira (1): sched/deadline: Unthrottle PI boosted threads while enqueuing
Lucas Stach (1): sched/deadline: Fix stale throttling on de-/boosted tasks
Juri Lelli (1): sched/deadline: Fix priority inheritance with multiple scheduling classes
Hui Su (1): kernel/sched: Remove dl_boosted flag comment
include/linux/sched.h | 13 ++-- kernel/sched/core.c | 11 ++-- kernel/sched/deadline.c | 131 +++++++++++++++++++++++++--------------- 3 files changed, 96 insertions(+), 59 deletions(-)
From: Daniel Bristot de Oliveira bristot@redhat.com
commit feff2e65efd8d84cf831668e182b2ce73c604bbb upstream.
stress-ng has a test (stress-ng --cyclic) that creates a set of threads under SCHED_DEADLINE with the following parameters:
dl_runtime = 10000 (10 us) dl_deadline = 100000 (100 us) dl_period = 100000 (100 us)
These parameters are very aggressive. When using a system without HRTICK set, these threads can easily execute longer than the dl_runtime because the throttling happens with 1/HZ resolution.
During the main part of the test, the system works just fine because the workload does not try to run over the 10 us. The problem happens at the end of the test, on the exit() path. During exit(), the threads need to do some cleanups that require real-time mutex locks, mainly those related to memory management, resulting in this scenario:
Note: locks are rt_mutexes... ------------------------------------------------------------------------ TASK A: TASK B: TASK C: activation activation activation
lock(a): OK! lock(b): OK! <overrun runtime> lock(a) -> block (task A owns it) -> self notice/set throttled +--< -> arm replenished timer | switch-out | lock(b) | -> <C prio > B prio> | -> boost TASK B | unlock(a) switch-out | -> handle lock a to B | -> wakeup(B) | -> B is throttled: | -> do not enqueue | switch-out | | +---------------------> replenishment timer -> TASK B is boosted: -> do not enqueue ------------------------------------------------------------------------
BOOM: TASK B is runnable but !enqueued, holding TASK C: the system crashes with hung task C.
This problem is avoided by removing the throttle state from the boosted thread while boosting it (by TASK A in the example above), allowing it to be queued and run boosted.
The next replenishment will take care of the runtime overrun, pushing the deadline further away. See the "while (dl_se->runtime <= 0)" on replenish_dl_entity() for more information.
Reported-by: Mark Simmons msimmons@redhat.com Signed-off-by: Daniel Bristot de Oliveira bristot@redhat.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Juri Lelli juri.lelli@redhat.com Tested-by: Mark Simmons msimmons@redhat.com Link: https://lkml.kernel.org/r/5076e003450835ec74e6fa5917d02c4fa41687e6.160017029... [Ankit: Regenerated the patch for v4.19.y] Signed-off-by: Ankit Jain ankitja@vmware.com --- kernel/sched/deadline.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index beec5081a55a..1f8444d9df9d 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1484,6 +1484,27 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) */ if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) { pi_se = &pi_task->dl; + /* + * Because of delays in the detection of the overrun of a + * thread's runtime, it might be the case that a thread + * goes to sleep in a rt mutex with negative runtime. As + * a consequence, the thread will be throttled. + * + * While waiting for the mutex, this thread can also be + * boosted via PI, resulting in a thread that is throttled + * and boosted at the same time. + * + * In this case, the boost overrides the throttle. + */ + if (p->dl.dl_throttled) { + /* + * The replenish timer needs to be canceled. No + * problem if it fires concurrently: boosted threads + * are ignored in dl_task_timer(). + */ + hrtimer_try_to_cancel(&p->dl.dl_timer); + p->dl.dl_throttled = 0; + } } else if (!dl_prio(p->normal_prio)) { /* * Special case in which we have a !SCHED_DEADLINE task
From: Lucas Stach l.stach@pengutronix.de
commit 46fcc4b00c3cca8adb9b7c9afdd499f64e427135 upstream.
When a boosted task gets throttled, what normally happens is that it's immediately enqueued again with ENQUEUE_REPLENISH, which replenishes the runtime and clears the dl_throttled flag. There is a special case however: if the throttling happened on sched-out and the task has been deboosted in the meantime, the replenish is skipped as the task will return to its normal scheduling class. This leaves the task with the dl_throttled flag set.
Now if the task gets boosted up to the deadline scheduling class again while it is sleeping, it's still in the throttled state. The normal wakeup however will enqueue the task with ENQUEUE_REPLENISH not set, so we don't actually place it on the rq. Thus we end up with a task that is runnable, but not actually on the rq and neither a immediate replenishment happens, nor is the replenishment timer set up, so the task is stuck in forever-throttled limbo.
Clear the dl_throttled flag before dropping back to the normal scheduling class to fix this issue.
Signed-off-by: Lucas Stach l.stach@pengutronix.de Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Juri Lelli juri.lelli@redhat.com Link: https://lkml.kernel.org/r/20200831110719.2126930-1-l.stach@pengutronix.de [Ankit: Regenerated the patch for v4.19.y] Signed-off-by: Ankit Jain ankitja@vmware.com --- kernel/sched/deadline.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 1f8444d9df9d..29cd4c0a92c0 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1507,12 +1507,15 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) } } else if (!dl_prio(p->normal_prio)) { /* - * Special case in which we have a !SCHED_DEADLINE task - * that is going to be deboosted, but exceeds its - * runtime while doing so. No point in replenishing - * it, as it's going to return back to its original - * scheduling class after this. + * Special case in which we have a !SCHED_DEADLINE task that is going + * to be deboosted, but exceeds its runtime while doing so. No point in + * replenishing it, as it's going to return back to its original + * scheduling class after this. If it has been throttled, we need to + * clear the flag, otherwise the task may wake up as throttled after + * being boosted again with no means to replenish the runtime and clear + * the throttle. */ + p->dl.dl_throttled = 0; BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH); return; }
From: Juri Lelli juri.lelli@redhat.com
commit 2279f540ea7d05f22d2f0c4224319330228586bc upstream.
Glenn reported that "an application [he developed produces] a BUG in deadline.c when a SCHED_DEADLINE task contends with CFS tasks on nested PTHREAD_PRIO_INHERIT mutexes. I believe the bug is triggered when a CFS task that was boosted by a SCHED_DEADLINE task boosts another CFS task (nested priority inheritance).
------------[ cut here ]------------ kernel BUG at kernel/sched/deadline.c:1462! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 12 PID: 19171 Comm: dl_boost_bug Tainted: ... Hardware name: ... RIP: 0010:enqueue_task_dl+0x335/0x910 Code: ... RSP: 0018:ffffc9000c2bbc68 EFLAGS: 00010002 RAX: 0000000000000009 RBX: ffff888c0af94c00 RCX: ffffffff81e12500 RDX: 000000000000002e RSI: ffff888c0af94c00 RDI: ffff888c10b22600 RBP: ffffc9000c2bbd08 R08: 0000000000000009 R09: 0000000000000078 R10: ffffffff81e12440 R11: ffffffff81e1236c R12: ffff888bc8932600 R13: ffff888c0af94eb8 R14: ffff888c10b22600 R15: ffff888bc8932600 FS: 00007fa58ac55700(0000) GS:ffff888c10b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa58b523230 CR3: 0000000bf44ab003 CR4: 00000000007606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ? intel_pstate_update_util_hwp+0x13/0x170 rt_mutex_setprio+0x1cc/0x4b0 task_blocks_on_rt_mutex+0x225/0x260 rt_spin_lock_slowlock_locked+0xab/0x2d0 rt_spin_lock_slowlock+0x50/0x80 hrtimer_grab_expiry_lock+0x20/0x30 hrtimer_cancel+0x13/0x30 do_nanosleep+0xa0/0x150 hrtimer_nanosleep+0xe1/0x230 ? __hrtimer_init_sleeper+0x60/0x60 __x64_sys_nanosleep+0x8d/0xa0 do_syscall_64+0x4a/0x100 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fa58b52330d ... ---[ end trace 0000000000000002 ]—
He also provided a simple reproducer creating the situation below:
So the execution order of locking steps are the following (N1 and N2 are non-deadline tasks. D1 is a deadline task. M1 and M2 are mutexes that are enabled * with priority inheritance.)
Time moves forward as this timeline goes down:
N1 N2 D1 | | | | | | Lock(M1) | | | | | | Lock(M2) | | | | | | Lock(M2) | | | | Lock(M1) | | (!!bug triggered!) |
Daniel reported a similar situation as well, by just letting ksoftirqd run with DEADLINE (and eventually block on a mutex).
Problem is that boosted entities (Priority Inheritance) use static DEADLINE parameters of the top priority waiter. However, there might be cases where top waiter could be a non-DEADLINE entity that is currently boosted by a DEADLINE entity from a different lock chain (i.e., nested priority chains involving entities of non-DEADLINE classes). In this case, top waiter static DEADLINE parameters could be null (initialized to 0 at fork()) and replenish_dl_entity() would hit a BUG().
Fix this by keeping track of the original donor and using its parameters when a task is boosted.
Reported-by: Glenn Elliott glenn@aurora.tech Reported-by: Daniel Bristot de Oliveira bristot@redhat.com Signed-off-by: Juri Lelli juri.lelli@redhat.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Tested-by: Daniel Bristot de Oliveira bristot@redhat.com Link: https://lkml.kernel.org/r/20201117061432.517340-1-juri.lelli@redhat.com [Ankit: Regenerated the patch for v4.19.y] Signed-off-by: Ankit Jain ankitja@vmware.com --- include/linux/sched.h | 10 ++++- kernel/sched/core.c | 11 ++--- kernel/sched/deadline.c | 97 ++++++++++++++++++++++------------------- 3 files changed, 68 insertions(+), 50 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index f92d5ae6d04e..2d77bfbac595 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -546,7 +546,6 @@ struct sched_dl_entity { * overruns. */ unsigned int dl_throttled : 1; - unsigned int dl_boosted : 1; unsigned int dl_yielded : 1; unsigned int dl_non_contending : 1; unsigned int dl_overrun : 1; @@ -565,6 +564,15 @@ struct sched_dl_entity { * time. */ struct hrtimer inactive_timer; + +#ifdef CONFIG_RT_MUTEXES + /* + * Priority Inheritance. When a DEADLINE scheduling entity is boosted + * pi_se points to the donor, otherwise points to the dl_se it belongs + * to (the original one/itself). + */ + struct sched_dl_entity *pi_se; +#endif };
union rcu_special { diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 32af895bd86b..a03464249771 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3869,20 +3869,21 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) if (!dl_prio(p->normal_prio) || (pi_task && dl_prio(pi_task->prio) && dl_entity_preempt(&pi_task->dl, &p->dl))) { - p->dl.dl_boosted = 1; + p->dl.pi_se = pi_task->dl.pi_se; queue_flag |= ENQUEUE_REPLENISH; - } else - p->dl.dl_boosted = 0; + } else { + p->dl.pi_se = &p->dl; + } p->sched_class = &dl_sched_class; } else if (rt_prio(prio)) { if (dl_prio(oldprio)) - p->dl.dl_boosted = 0; + p->dl.pi_se = &p->dl; if (oldprio < prio) queue_flag |= ENQUEUE_HEAD; p->sched_class = &rt_sched_class; } else { if (dl_prio(oldprio)) - p->dl.dl_boosted = 0; + p->dl.pi_se = &p->dl; if (rt_prio(oldprio)) p->rt.timeout = 0; p->sched_class = &fair_sched_class; diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 29cd4c0a92c0..29ed5d8d30d6 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -43,6 +43,28 @@ static inline int on_dl_rq(struct sched_dl_entity *dl_se) return !RB_EMPTY_NODE(&dl_se->rb_node); }
+#ifdef CONFIG_RT_MUTEXES +static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se) +{ + return dl_se->pi_se; +} + +static inline bool is_dl_boosted(struct sched_dl_entity *dl_se) +{ + return pi_of(dl_se) != dl_se; +} +#else +static inline struct sched_dl_entity *pi_of(struct sched_dl_entity *dl_se) +{ + return dl_se; +} + +static inline bool is_dl_boosted(struct sched_dl_entity *dl_se) +{ + return false; +} +#endif + #ifdef CONFIG_SMP static inline struct dl_bw *dl_bw_of(int i) { @@ -657,7 +679,7 @@ static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq);
- WARN_ON(dl_se->dl_boosted); + WARN_ON(is_dl_boosted(dl_se)); WARN_ON(dl_time_before(rq_clock(rq), dl_se->deadline));
/* @@ -695,21 +717,20 @@ static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se) * could happen are, typically, a entity voluntarily trying to overcome its * runtime, or it just underestimated it during sched_setattr(). */ -static void replenish_dl_entity(struct sched_dl_entity *dl_se, - struct sched_dl_entity *pi_se) +static void replenish_dl_entity(struct sched_dl_entity *dl_se) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq);
- BUG_ON(pi_se->dl_runtime <= 0); + BUG_ON(pi_of(dl_se)->dl_runtime <= 0);
/* * This could be the case for a !-dl task that is boosted. * Just go with full inherited parameters. */ if (dl_se->dl_deadline == 0) { - dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; - dl_se->runtime = pi_se->dl_runtime; + dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline; + dl_se->runtime = pi_of(dl_se)->dl_runtime; }
if (dl_se->dl_yielded && dl_se->runtime > 0) @@ -722,8 +743,8 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se, * arbitrary large. */ while (dl_se->runtime <= 0) { - dl_se->deadline += pi_se->dl_period; - dl_se->runtime += pi_se->dl_runtime; + dl_se->deadline += pi_of(dl_se)->dl_period; + dl_se->runtime += pi_of(dl_se)->dl_runtime; }
/* @@ -737,8 +758,8 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se, */ if (dl_time_before(dl_se->deadline, rq_clock(rq))) { printk_deferred_once("sched: DL replenish lagged too much\n"); - dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; - dl_se->runtime = pi_se->dl_runtime; + dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline; + dl_se->runtime = pi_of(dl_se)->dl_runtime; }
if (dl_se->dl_yielded) @@ -771,8 +792,7 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se, * task with deadline equal to period this is the same of using * dl_period instead of dl_deadline in the equation above. */ -static bool dl_entity_overflow(struct sched_dl_entity *dl_se, - struct sched_dl_entity *pi_se, u64 t) +static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t) { u64 left, right;
@@ -794,9 +814,9 @@ static bool dl_entity_overflow(struct sched_dl_entity *dl_se, * of anything below microseconds resolution is actually fiction * (but still we want to give the user that illusion >;). */ - left = (pi_se->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE); + left = (pi_of(dl_se)->dl_deadline >> DL_SCALE) * (dl_se->runtime >> DL_SCALE); right = ((dl_se->deadline - t) >> DL_SCALE) * - (pi_se->dl_runtime >> DL_SCALE); + (pi_of(dl_se)->dl_runtime >> DL_SCALE);
return dl_time_before(right, left); } @@ -881,24 +901,23 @@ static inline bool dl_is_implicit(struct sched_dl_entity *dl_se) * Please refer to the comments update_dl_revised_wakeup() function to find * more about the Revised CBS rule. */ -static void update_dl_entity(struct sched_dl_entity *dl_se, - struct sched_dl_entity *pi_se) +static void update_dl_entity(struct sched_dl_entity *dl_se) { struct dl_rq *dl_rq = dl_rq_of_se(dl_se); struct rq *rq = rq_of_dl_rq(dl_rq);
if (dl_time_before(dl_se->deadline, rq_clock(rq)) || - dl_entity_overflow(dl_se, pi_se, rq_clock(rq))) { + dl_entity_overflow(dl_se, rq_clock(rq))) {
if (unlikely(!dl_is_implicit(dl_se) && !dl_time_before(dl_se->deadline, rq_clock(rq)) && - !dl_se->dl_boosted)){ + !is_dl_boosted(dl_se))) { update_dl_revised_wakeup(dl_se, rq); return; }
- dl_se->deadline = rq_clock(rq) + pi_se->dl_deadline; - dl_se->runtime = pi_se->dl_runtime; + dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline; + dl_se->runtime = pi_of(dl_se)->dl_runtime; } }
@@ -997,7 +1016,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer) * The task might have been boosted by someone else and might be in the * boosting/deboosting path, its not throttled. */ - if (dl_se->dl_boosted) + if (is_dl_boosted(dl_se)) goto unlock;
/* @@ -1025,7 +1044,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer) * but do not enqueue -- wait for our wakeup to do that. */ if (!task_on_rq_queued(p)) { - replenish_dl_entity(dl_se, dl_se); + replenish_dl_entity(dl_se); goto unlock; }
@@ -1115,7 +1134,7 @@ static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
if (dl_time_before(dl_se->deadline, rq_clock(rq)) && dl_time_before(rq_clock(rq), dl_next_period(dl_se))) { - if (unlikely(dl_se->dl_boosted || !start_dl_timer(p))) + if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(p))) return; dl_se->dl_throttled = 1; if (dl_se->runtime > 0) @@ -1246,7 +1265,7 @@ static void update_curr_dl(struct rq *rq) dl_se->dl_overrun = 1;
__dequeue_task_dl(rq, curr, 0); - if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr))) + if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(curr))) enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
if (!is_leftmost(curr, &rq->dl)) @@ -1440,8 +1459,7 @@ static void __dequeue_dl_entity(struct sched_dl_entity *dl_se) }
static void -enqueue_dl_entity(struct sched_dl_entity *dl_se, - struct sched_dl_entity *pi_se, int flags) +enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags) { BUG_ON(on_dl_rq(dl_se));
@@ -1452,9 +1470,9 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, */ if (flags & ENQUEUE_WAKEUP) { task_contending(dl_se, flags); - update_dl_entity(dl_se, pi_se); + update_dl_entity(dl_se); } else if (flags & ENQUEUE_REPLENISH) { - replenish_dl_entity(dl_se, pi_se); + replenish_dl_entity(dl_se); } else if ((flags & ENQUEUE_RESTORE) && dl_time_before(dl_se->deadline, rq_clock(rq_of_dl_rq(dl_rq_of_se(dl_se))))) { @@ -1471,19 +1489,7 @@ static void dequeue_dl_entity(struct sched_dl_entity *dl_se)
static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) { - struct task_struct *pi_task = rt_mutex_get_top_task(p); - struct sched_dl_entity *pi_se = &p->dl; - - /* - * Use the scheduling parameters of the top pi-waiter task if: - * - we have a top pi-waiter which is a SCHED_DEADLINE task AND - * - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is - * smaller than our deadline OR we are a !SCHED_DEADLINE task getting - * boosted due to a SCHED_DEADLINE pi-waiter). - * Otherwise we keep our runtime and deadline. - */ - if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) { - pi_se = &pi_task->dl; + if (is_dl_boosted(&p->dl)) { /* * Because of delays in the detection of the overrun of a * thread's runtime, it might be the case that a thread @@ -1516,7 +1522,7 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) * the throttle. */ p->dl.dl_throttled = 0; - BUG_ON(!p->dl.dl_boosted || flags != ENQUEUE_REPLENISH); + BUG_ON(!is_dl_boosted(&p->dl) || flags != ENQUEUE_REPLENISH); return; }
@@ -1553,7 +1559,7 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) return; }
- enqueue_dl_entity(&p->dl, pi_se, flags); + enqueue_dl_entity(&p->dl, flags);
if (!task_current(rq, p) && p->nr_cpus_allowed > 1) enqueue_pushable_dl_task(rq, p); @@ -2715,11 +2721,14 @@ void __dl_clear_params(struct task_struct *p) dl_se->dl_bw = 0; dl_se->dl_density = 0;
- dl_se->dl_boosted = 0; dl_se->dl_throttled = 0; dl_se->dl_yielded = 0; dl_se->dl_non_contending = 0; dl_se->dl_overrun = 0; + +#ifdef CONFIG_RT_MUTEXES + dl_se->pi_se = dl_se; +#endif }
bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
From: Hui Su suhui_kernel@163.com
commit 0e3872499de1a1230cef5221607d71aa09264bd5 upstream.
since commit 2279f540ea7d ("sched/deadline: Fix priority inheritance with multiple scheduling classes"), we should not keep it here.
Signed-off-by: Hui Su suhui_kernel@163.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Daniel Bristot de Oliveira bristot@redhat.com Link: https://lore.kernel.org/r/20220107095254.GA49258@localhost.localdomain [Ankit: Regenerated the patch for v4.19.y] Signed-off-by: Ankit Jain ankitja@vmware.com --- include/linux/sched.h | 4 ---- 1 file changed, 4 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index 2ed820558da1..bc04745da6c1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -528,10 +528,6 @@ struct sched_dl_entity { * task has to wait for a replenishment to be performed at the * next firing of dl_timer. * - * @dl_boosted tells if we are boosted due to DI. If so we are - * outside bandwidth enforcement mechanism (but only until we - * exit the critical section); - * * @dl_yielded tells if task gave up the CPU before consuming * all its available runtime during the last job. *
On Mon, Aug 22, 2022 at 01:13:44PM +0530, Ankit Jain wrote:
When a CFS task that was boosted by a SCHED_DEADLINE task boosts another CFS task (nested priority inheritance), Kernel panic is observed. Fixing priority inheritance changes the way how sched_deadline attributes are being inherited from original donor task.
Additional supporting patches are added to fix throttling of boosted tasks.
Daniel Bristot de Oliveira (1): sched/deadline: Unthrottle PI boosted threads while enqueuing
Lucas Stach (1): sched/deadline: Fix stale throttling on de-/boosted tasks
Juri Lelli (1): sched/deadline: Fix priority inheritance with multiple scheduling classes
Hui Su (1): kernel/sched: Remove dl_boosted flag comment
include/linux/sched.h | 13 ++-- kernel/sched/core.c | 11 ++-- kernel/sched/deadline.c | 131 +++++++++++++++++++++++++--------------- 3 files changed, 96 insertions(+), 59 deletions(-)
-- 2.34.1
Both sets of backports now queued up, thanks.
greg k-h
linux-stable-mirror@lists.linaro.org
-
Ankit Jain -
Greg KH