From: Linus Torvalds <torvalds(a)linux-foundation.org>
Commit eb66ae030829605d61fbef1909ce310e29f78821 upstream.
This is a backport to stable 4.4.y.
Jann Horn points out that our TLB flushing was subtly wrong for the
mremap() case. What makes mremap() special is that we don't follow the
usual "add page to list of pages to be freed, then flush tlb, and then
free pages". No, mremap() obviously just _moves_ the page from one page
table location to another.
That matters, because mremap() thus doesn't directly control the
lifetime of the moved page with a freelist: instead, the lifetime of the
page is controlled by the page table locking, that serializes access to
the entry.
As a result, we need to flush the TLB not just before releasing the lock
for the source location (to avoid any concurrent accesses to the entry),
but also before we release the destination page table lock (to avoid the
TLB being flushed after somebody else has already done something to that
page).
This also makes the whole "need_flush" logic unnecessary, since we now
always end up flushing the TLB for every valid entry.
Reported-and-tested-by: Jann Horn <jannh(a)google.com>
Acked-by: Will Deacon <will.deacon(a)arm.com>
Tested-by: Ingo Molnar <mingo(a)kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz(a)infradead.org>
Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
[will: backport to 4.4 stable]
Signed-off-by: Will Deacon <will.deacon(a)arm.com>
---
mm/huge_memory.c | 6 +++++-
mm/mremap.c | 21 ++++++++++++++++-----
2 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c4ea57ee2fd1..465786cd6490 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1511,7 +1511,7 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
spinlock_t *old_ptl, *new_ptl;
int ret = 0;
pmd_t pmd;
-
+ bool force_flush = false;
struct mm_struct *mm = vma->vm_mm;
if ((old_addr & ~HPAGE_PMD_MASK) ||
@@ -1539,6 +1539,8 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
if (new_ptl != old_ptl)
spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
+ if (pmd_present(pmd))
+ force_flush = true;
VM_BUG_ON(!pmd_none(*new_pmd));
if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
@@ -1547,6 +1549,8 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
}
set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
+ if (force_flush)
+ flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
if (new_ptl != old_ptl)
spin_unlock(new_ptl);
spin_unlock(old_ptl);
diff --git a/mm/mremap.c b/mm/mremap.c
index fe7b7f65f4f4..450b306d473e 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -96,6 +96,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
struct mm_struct *mm = vma->vm_mm;
pte_t *old_pte, *new_pte, pte;
spinlock_t *old_ptl, *new_ptl;
+ bool force_flush = false;
+ unsigned long len = old_end - old_addr;
/*
* When need_rmap_locks is true, we take the i_mmap_rwsem and anon_vma
@@ -143,12 +145,26 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
if (pte_none(*old_pte))
continue;
pte = ptep_get_and_clear(mm, old_addr, old_pte);
+ /*
+ * If we are remapping a valid PTE, make sure
+ * to flush TLB before we drop the PTL for the PTE.
+ *
+ * NOTE! Both old and new PTL matter: the old one
+ * for racing with page_mkclean(), the new one to
+ * make sure the physical page stays valid until
+ * the TLB entry for the old mapping has been
+ * flushed.
+ */
+ if (pte_present(pte))
+ force_flush = true;
pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
pte = move_soft_dirty_pte(pte);
set_pte_at(mm, new_addr, new_pte, pte);
}
arch_leave_lazy_mmu_mode();
+ if (force_flush)
+ flush_tlb_range(vma, old_end - len, old_end);
if (new_ptl != old_ptl)
spin_unlock(new_ptl);
pte_unmap(new_pte - 1);
@@ -168,7 +184,6 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
{
unsigned long extent, next, old_end;
pmd_t *old_pmd, *new_pmd;
- bool need_flush = false;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
@@ -207,7 +222,6 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
anon_vma_unlock_write(vma->anon_vma);
}
if (err > 0) {
- need_flush = true;
continue;
} else if (!err) {
split_huge_page_pmd(vma, old_addr, old_pmd);
@@ -224,10 +238,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
extent = LATENCY_LIMIT;
move_ptes(vma, old_pmd, old_addr, old_addr + extent,
new_vma, new_pmd, new_addr, need_rmap_locks);
- need_flush = true;
}
- if (likely(need_flush))
- flush_tlb_range(vma, old_end-len, old_addr);
mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
--
2.1.4
There's no point to register the cpuidle driver for the current CPU, when
the initialization of the arch specific back-end data fails by returning
-ENXIO.
Instead, let's re-order the sequence to its original flow, by first trying
to initialize the back-end part and then act accordingly on the returned
error code. Additionally, let's print the error message, no matter of what
error code that was returned.
Signed-off-by: Ulf Hansson <ulf.hansson(a)linaro.org>
Fixes: a0d46a3dfdc3 ("ARM: cpuidle: Register per cpuidle device")
Cc: <stable(a)vger.kernel.org> # v4.19+
---
Changes in v2:
- Added a fixes and a stable tag.
---
drivers/cpuidle/cpuidle-arm.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index 073557f433eb..df564d783216 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -103,13 +103,6 @@ static int __init arm_idle_init_cpu(int cpu)
goto out_kfree_drv;
}
- ret = cpuidle_register_driver(drv);
- if (ret) {
- if (ret != -EBUSY)
- pr_err("Failed to register cpuidle driver\n");
- goto out_kfree_drv;
- }
-
/*
* Call arch CPU operations in order to initialize
* idle states suspend back-end specific data
@@ -117,15 +110,20 @@ static int __init arm_idle_init_cpu(int cpu)
ret = arm_cpuidle_init(cpu);
/*
- * Skip the cpuidle device initialization if the reported
+ * Allow the initialization to continue for other CPUs, if the reported
* failure is a HW misconfiguration/breakage (-ENXIO).
*/
- if (ret == -ENXIO)
- return 0;
-
if (ret) {
pr_err("CPU %d failed to init idle CPU ops\n", cpu);
- goto out_unregister_drv;
+ ret = ret == -ENXIO ? 0 : ret;
+ goto out_kfree_drv;
+ }
+
+ ret = cpuidle_register_driver(drv);
+ if (ret) {
+ if (ret != -EBUSY)
+ pr_err("Failed to register cpuidle driver\n");
+ goto out_kfree_drv;
}
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
--
2.17.1
Quoting Dean Wallace (2018-10-25 16:25:17)
> I have found a regression in 4.18.15 that means I lose sound on my old
> Toshiba Chromebook 2 (Swanky). My system details are:-
>
> Toshiba Chromebook (Swanky)
> MrChromebox UEFI coreboot
> Arch Linux running latest alsa/pulseaudio
>
> Upgraded kernel from 4.18.14 to 4.18.15 and lost all sound output. By
> output I mean, the card is still detected, the module loaded, all apps
> showing sound is being playing, but no actual audible sound comes
> through. Upgraded to 4.18.16 same issue.
>
> Dug around and found Upstream commit 648e921888ad96ea3dc922739e96716ad3225d7f
> clk: x86: Stop marking clocks as CLK_IS_CRITICAL
> "This commit removes the CLK_IS_CRITICAL marking, fixing Cherry Trail
> devices not being able to reach S0i3 greatly decreasing their battery
> drain when suspended."
>
> I reverted it and compiled 4.18.16 and have sound back again. Could
> this be looked into, with possibility of fix.
>
Thanks for the bug report. I'm adding some people involved in the commit
you mention is causing audio regressions. The best plan is to probably
revert the commit from the 4.18 linux stable tree. Or there may be
another patch missing that would be useful to make this backported patch
work. Hopefully Hans or Andy knows.
This is an automatic generated email to let you know that the following patch were queued:
Subject: media: v4l: event: Prevent freeing event subscriptions while accessed
Author: Sakari Ailus <sakari.ailus(a)linux.intel.com>
Date: Tue Sep 11 05:32:37 2018 -0400
The event subscriptions are added to the subscribed event list while
holding a spinlock, but that lock is subsequently released while still
accessing the subscription object. This makes it possible to unsubscribe
the event --- and freeing the subscription object's memory --- while
the subscription object is simultaneously accessed.
Prevent this by adding a mutex to serialise the event subscription and
unsubscription. This also gives a guarantee to the callback ops that the
add op has returned before the del op is called.
This change also results in making the elems field less special:
subscriptions are only added to the event list once they are fully
initialised.
Signed-off-by: Sakari Ailus <sakari.ailus(a)linux.intel.com>
Reviewed-by: Hans Verkuil <hans.verkuil(a)cisco.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart(a)ideasonboard.com>
Cc: stable(a)vger.kernel.org # for 4.14 and up
Fixes: c3b5b0241f62 ("V4L/DVB: V4L: Events: Add backend")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung(a)kernel.org>
drivers/media/v4l2-core/v4l2-event.c | 38 +++++++++++++++++++-----------------
drivers/media/v4l2-core/v4l2-fh.c | 2 ++
include/media/v4l2-fh.h | 4 ++++
3 files changed, 26 insertions(+), 18 deletions(-)
---
diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c
index 127fe6eb91d9..a3ef1f50a4b3 100644
--- a/drivers/media/v4l2-core/v4l2-event.c
+++ b/drivers/media/v4l2-core/v4l2-event.c
@@ -115,14 +115,6 @@ static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *e
if (sev == NULL)
return;
- /*
- * If the event has been added to the fh->subscribed list, but its
- * add op has not completed yet elems will be 0, treat this as
- * not being subscribed.
- */
- if (!sev->elems)
- return;
-
/* Increase event sequence number on fh. */
fh->sequence++;
@@ -208,6 +200,7 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
struct v4l2_subscribed_event *sev, *found_ev;
unsigned long flags;
unsigned i;
+ int ret = 0;
if (sub->type == V4L2_EVENT_ALL)
return -EINVAL;
@@ -225,31 +218,36 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
sev->flags = sub->flags;
sev->fh = fh;
sev->ops = ops;
+ sev->elems = elems;
+
+ mutex_lock(&fh->subscribe_lock);
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
- if (!found_ev)
- list_add(&sev->list, &fh->subscribed);
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
if (found_ev) {
+ /* Already listening */
kvfree(sev);
- return 0; /* Already listening */
+ goto out_unlock;
}
if (sev->ops && sev->ops->add) {
- int ret = sev->ops->add(sev, elems);
+ ret = sev->ops->add(sev, elems);
if (ret) {
- sev->ops = NULL;
- v4l2_event_unsubscribe(fh, sub);
- return ret;
+ kvfree(sev);
+ goto out_unlock;
}
}
- /* Mark as ready for use */
- sev->elems = elems;
+ spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+ list_add(&sev->list, &fh->subscribed);
+ spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
- return 0;
+out_unlock:
+ mutex_unlock(&fh->subscribe_lock);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
@@ -288,6 +286,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
return 0;
}
+ mutex_lock(&fh->subscribe_lock);
+
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
sev = v4l2_event_subscribed(fh, sub->type, sub->id);
@@ -305,6 +305,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
if (sev && sev->ops && sev->ops->del)
sev->ops->del(sev);
+ mutex_unlock(&fh->subscribe_lock);
+
kvfree(sev);
return 0;
diff --git a/drivers/media/v4l2-core/v4l2-fh.c b/drivers/media/v4l2-core/v4l2-fh.c
index 3895999bf880..c91a7bd3ecfc 100644
--- a/drivers/media/v4l2-core/v4l2-fh.c
+++ b/drivers/media/v4l2-core/v4l2-fh.c
@@ -45,6 +45,7 @@ void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
INIT_LIST_HEAD(&fh->available);
INIT_LIST_HEAD(&fh->subscribed);
fh->sequence = -1;
+ mutex_init(&fh->subscribe_lock);
}
EXPORT_SYMBOL_GPL(v4l2_fh_init);
@@ -90,6 +91,7 @@ void v4l2_fh_exit(struct v4l2_fh *fh)
return;
v4l_disable_media_source(fh->vdev);
v4l2_event_unsubscribe_all(fh);
+ mutex_destroy(&fh->subscribe_lock);
fh->vdev = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_fh_exit);
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
index ea73fef8bdc0..8586cfb49828 100644
--- a/include/media/v4l2-fh.h
+++ b/include/media/v4l2-fh.h
@@ -38,10 +38,13 @@ struct v4l2_ctrl_handler;
* @prio: priority of the file handler, as defined by &enum v4l2_priority
*
* @wait: event' s wait queue
+ * @subscribe_lock: serialise changes to the subscribed list; guarantee that
+ * the add and del event callbacks are orderly called
* @subscribed: list of subscribed events
* @available: list of events waiting to be dequeued
* @navailable: number of available events at @available list
* @sequence: event sequence number
+ *
* @m2m_ctx: pointer to &struct v4l2_m2m_ctx
*/
struct v4l2_fh {
@@ -52,6 +55,7 @@ struct v4l2_fh {
/* Events */
wait_queue_head_t wait;
+ struct mutex subscribe_lock;
struct list_head subscribed;
struct list_head available;
unsigned int navailable;