* lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq()
@ 2015-10-21 13:20 Luca Abeni
2015-10-22 5:35 ` Wanpeng Li
0 siblings, 1 reply; 6+ messages in thread
From: Luca Abeni @ 2015-10-21 13:20 UTC (permalink / raw)
To: linux-kernel; +Cc: Peter Zijlstra, Ingo Molnar, Juri Lelli
Hi all,
after fixing task migrations for SCHED_DEADLINE, I started to see some
lockdep-related warnings that look like this:
[ 794.428081] WARNING: CPU: 1 PID: 0 at /home/luca/Src/GRUB/linux-reclaiming/kernel/locking/lockdep.c:3407 lock_release+0x3f4/0x440()
[ 794.428439] releasing a pinned lock
[ 794.428439] Modules linked in:
[ 794.428439] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.3.0-rc5+ #32
[ 794.428439] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Bochs 01/01/2011
[ 794.428439] ffffffff81c946d0 ffff880007b03cc8 ffffffff8135abd2 ffff880007b03d10
[ 794.428439] ffff880007b03d00 ffffffff810546f1 ffff880007b159d8 ffffffff81096663
[ 794.428439] ffff88000754c558 0000000000000001 ffff88000754bd80 ffff880007b03d60
[ 794.428439] Call Trace:
[ 794.428439] <IRQ> [<ffffffff8135abd2>] dump_stack+0x4b/0x69
[ 794.428439] [<ffffffff810546f1>] warn_slowpath_common+0x81/0xc0
[ 794.428439] [<ffffffff81096663>] ? find_lock_later_rq+0x103/0x180
[ 794.428439] [<ffffffff81054777>] warn_slowpath_fmt+0x47/0x50
[ 794.428439] [<ffffffff8109feb4>] lock_release+0x3f4/0x440
[ 794.428439] [<ffffffff8194215a>] _raw_spin_unlock+0x1a/0x30
[ 794.428439] [<ffffffff81096663>] find_lock_later_rq+0x103/0x180
[ 794.428439] [<ffffffff81096741>] push_dl_task.part.33+0x61/0x190
[ 794.428439] [<ffffffff81096a94>] dl_task_timer+0x194/0x2e0
[ 794.428439] [<ffffffff81096900>] ? task_woken_dl+0x60/0x60
[ 794.428439] [<ffffffff810c3a87>] __hrtimer_run_queues+0x107/0x470
[ 794.428439] [<ffffffff810c3f82>] ? hrtimer_interrupt+0x82/0x1b0
[ 794.428439] [<ffffffff810c3fa6>] hrtimer_interrupt+0xa6/0x1b0
[ 794.428439] [<ffffffff81039570>] local_apic_timer_interrupt+0x30/0x60
[ 794.428439] [<ffffffff81039ee8>] smp_apic_timer_interrupt+0x38/0x50
[ 794.428439] [<ffffffff819436c4>] apic_timer_interrupt+0x84/0x90
[ 794.428439] <EOI> [<ffffffff8100ea3b>] ? default_idle+0x1b/0x140
[ 794.428439] [<ffffffff8100ea39>] ? default_idle+0x19/0x140
[ 794.428439] [<ffffffff8100f25a>] arch_cpu_idle+0xa/0x10
[ 794.428439] [<ffffffff81097e45>] default_idle_call+0x25/0x40
[ 794.428439] [<ffffffff810981d0>] cpu_startup_entry+0x310/0x390
[ 794.428439] [<ffffffff810380c3>] start_secondary+0xf3/0x100
[ 794.428439] ---[ end trace 1d35bf076299f814 ]---
(this happended on KVM, but I can trigger similar warnings on real hardware too).
This was not happening before my last patch, because push_dl_task() never migrated
any task, and always returned before calling find_lock_later_rq()...
Now, if I understand correctly the issue is that dl_task_timer() does:
rq = task_rq_lock(p, &flags);
[...]
if (has_pushable_dl_tasks(rq))
push_dl_task(rq);
with task_rq_lock() that pins rq->lock and push_tl_task() that invokes
find_lock_later_rq() that unlocks rq->lock() while it is pinned.
I am not sure about how to fix this issue: as a first try, I did
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 142df26..5b1ba95 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -668,8 +668,11 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
* Queueing this task back might have overloaded rq, check if we need
* to kick someone away.
*/
- if (has_pushable_dl_tasks(rq))
+ if (has_pushable_dl_tasks(rq)) {
+ lockdep_unpin_lock(&rq->lock);
push_dl_task(rq);
+ lockdep_pin_lock(&rq->lock);
+ }
#endif
unlock:
This removes the warning, but I am not sure if it is the correct fix (is it
valid to unpin rq->lock, here?).
If someone can confirm that this is the correct approach, I'll test the patch a
little bit more and then I'll send a properly signed-off patch; otherwise, if
someone can suggest the correct approach I'll try it.
Thanks,
Luca
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq()
2015-10-21 13:20 lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq() Luca Abeni
@ 2015-10-22 5:35 ` Wanpeng Li
2015-10-22 7:06 ` Luca Abeni
0 siblings, 1 reply; 6+ messages in thread
From: Wanpeng Li @ 2015-10-22 5:35 UTC (permalink / raw)
To: Luca Abeni, linux-kernel; +Cc: Peter Zijlstra, Ingo Molnar, Juri Lelli
On 10/21/15 9:20 PM, Luca Abeni wrote:
> Hi all,
>
> after fixing task migrations for SCHED_DEADLINE, I started to see some
> lockdep-related warnings that look like this:
> [ 794.428081] WARNING: CPU: 1 PID: 0 at
> /home/luca/Src/GRUB/linux-reclaiming/kernel/locking/lockdep.c:3407
> lock_release+0x3f4/0x440()
> [ 794.428439] releasing a pinned lock
> [ 794.428439] Modules linked in:
> [ 794.428439] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.3.0-rc5+ #32
> [ 794.428439] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
> BIOS Bochs 01/01/2011
> [ 794.428439] ffffffff81c946d0 ffff880007b03cc8 ffffffff8135abd2
> ffff880007b03d10
> [ 794.428439] ffff880007b03d00 ffffffff810546f1 ffff880007b159d8
> ffffffff81096663
> [ 794.428439] ffff88000754c558 0000000000000001 ffff88000754bd80
> ffff880007b03d60
> [ 794.428439] Call Trace:
> [ 794.428439] <IRQ> [<ffffffff8135abd2>] dump_stack+0x4b/0x69
> [ 794.428439] [<ffffffff810546f1>] warn_slowpath_common+0x81/0xc0
> [ 794.428439] [<ffffffff81096663>] ? find_lock_later_rq+0x103/0x180
> [ 794.428439] [<ffffffff81054777>] warn_slowpath_fmt+0x47/0x50
> [ 794.428439] [<ffffffff8109feb4>] lock_release+0x3f4/0x440
> [ 794.428439] [<ffffffff8194215a>] _raw_spin_unlock+0x1a/0x30
> [ 794.428439] [<ffffffff81096663>] find_lock_later_rq+0x103/0x180
> [ 794.428439] [<ffffffff81096741>] push_dl_task.part.33+0x61/0x190
> [ 794.428439] [<ffffffff81096a94>] dl_task_timer+0x194/0x2e0
> [ 794.428439] [<ffffffff81096900>] ? task_woken_dl+0x60/0x60
> [ 794.428439] [<ffffffff810c3a87>] __hrtimer_run_queues+0x107/0x470
> [ 794.428439] [<ffffffff810c3f82>] ? hrtimer_interrupt+0x82/0x1b0
> [ 794.428439] [<ffffffff810c3fa6>] hrtimer_interrupt+0xa6/0x1b0
> [ 794.428439] [<ffffffff81039570>] local_apic_timer_interrupt+0x30/0x60
> [ 794.428439] [<ffffffff81039ee8>] smp_apic_timer_interrupt+0x38/0x50
> [ 794.428439] [<ffffffff819436c4>] apic_timer_interrupt+0x84/0x90
> [ 794.428439] <EOI> [<ffffffff8100ea3b>] ? default_idle+0x1b/0x140
> [ 794.428439] [<ffffffff8100ea39>] ? default_idle+0x19/0x140
> [ 794.428439] [<ffffffff8100f25a>] arch_cpu_idle+0xa/0x10
> [ 794.428439] [<ffffffff81097e45>] default_idle_call+0x25/0x40
> [ 794.428439] [<ffffffff810981d0>] cpu_startup_entry+0x310/0x390
> [ 794.428439] [<ffffffff810380c3>] start_secondary+0xf3/0x100
> [ 794.428439] ---[ end trace 1d35bf076299f814 ]---
> (this happended on KVM, but I can trigger similar warnings on real
> hardware too).
>
> This was not happening before my last patch, because push_dl_task()
> never migrated
> any task, and always returned before calling find_lock_later_rq()...
>
> Now, if I understand correctly the issue is that dl_task_timer() does:
> rq = task_rq_lock(p, &flags);
> [...]
> if (has_pushable_dl_tasks(rq))
> push_dl_task(rq);
> with task_rq_lock() that pins rq->lock and push_tl_task() that invokes
> find_lock_later_rq() that unlocks rq->lock() while it is pinned.
>
> I am not sure about how to fix this issue: as a first try, I did
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 142df26..5b1ba95 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -668,8 +668,11 @@ static enum hrtimer_restart dl_task_timer(struct
> hrtimer *timer)
> * Queueing this task back might have overloaded rq, check if we
> need
> * to kick someone away.
> */
> - if (has_pushable_dl_tasks(rq))
> + if (has_pushable_dl_tasks(rq)) {
> + lockdep_unpin_lock(&rq->lock);
> push_dl_task(rq);
> + lockdep_pin_lock(&rq->lock);
> + }
> #endif
>
> unlock:
>
> This removes the warning, but I am not sure if it is the correct fix
> (is it
> valid to unpin rq->lock, here?).
>
> If someone can confirm that this is the correct approach, I'll test
> the patch a
> little bit more and then I'll send a properly signed-off patch;
> otherwise, if
> someone can suggest the correct approach I'll try it.
wake_up_new_task()
-> __task_rq_lock()
-> task_woken()
-> push_dl/rt_tasks()
-> push_dl/rt_task()
I think you also should consider the lockdep pin_lock in this path.
Regards,
Wanpeng Li
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq()
2015-10-22 5:35 ` Wanpeng Li
@ 2015-10-22 7:06 ` Luca Abeni
2015-10-23 9:50 ` Peter Zijlstra
0 siblings, 1 reply; 6+ messages in thread
From: Luca Abeni @ 2015-10-22 7:06 UTC (permalink / raw)
To: Wanpeng Li, linux-kernel; +Cc: Peter Zijlstra, Ingo Molnar, Juri Lelli
Hi,
On 10/22/2015 07:35 AM, Wanpeng Li wrote:
[...]
>> Now, if I understand correctly the issue is that dl_task_timer() does:
>> rq = task_rq_lock(p, &flags);
>> [...]
>> if (has_pushable_dl_tasks(rq))
>> push_dl_task(rq);
>> with task_rq_lock() that pins rq->lock and push_tl_task() that invokes
>> find_lock_later_rq() that unlocks rq->lock() while it is pinned.
>>
>> I am not sure about how to fix this issue: as a first try, I did
>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>> index 142df26..5b1ba95 100644
>> --- a/kernel/sched/deadline.c
>> +++ b/kernel/sched/deadline.c
>> @@ -668,8 +668,11 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
>> * Queueing this task back might have overloaded rq, check if we need
>> * to kick someone away.
>> */
>> - if (has_pushable_dl_tasks(rq))
>> + if (has_pushable_dl_tasks(rq)) {
>> + lockdep_unpin_lock(&rq->lock);
>> push_dl_task(rq);
>> + lockdep_pin_lock(&rq->lock);
>> + }
>> #endif
>>
>> unlock:
>>
>> This removes the warning, but I am not sure if it is the correct fix (is it
>> valid to unpin rq->lock, here?).
>>
>> If someone can confirm that this is the correct approach, I'll test the patch a
>> little bit more and then I'll send a properly signed-off patch; otherwise, if
>> someone can suggest the correct approach I'll try it.
>
> wake_up_new_task()
> -> __task_rq_lock()
> -> task_woken()
> -> push_dl/rt_tasks()
> -> push_dl/rt_task()
>
> I think you also should consider the lockdep pin_lock in this path.
Well, I never triggered this warning for the task_woken() path, but now I
see it... Thanks!
If someone can confirm that unpinning before calling push/pull and pinning again
after the call is the correct thing to do, I'll send a proper patch taking into
account all the paths... But for the moment I am still not sure if unpinning
the lock here is ok.
Thanks,
Luca
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq()
2015-10-22 7:06 ` Luca Abeni
@ 2015-10-23 9:50 ` Peter Zijlstra
2015-10-23 10:03 ` [tip:sched/urgent] sched/core: Add missing lockdep_unpin() annotations tip-bot for Peter Zijlstra
2015-10-23 20:10 ` lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq() Luca Abeni
0 siblings, 2 replies; 6+ messages in thread
From: Peter Zijlstra @ 2015-10-23 9:50 UTC (permalink / raw)
To: Luca Abeni; +Cc: Wanpeng Li, linux-kernel, Ingo Molnar, Juri Lelli
On Thu, Oct 22, 2015 at 09:06:31AM +0200, Luca Abeni wrote:
> >>diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> >>index 142df26..5b1ba95 100644
> >>--- a/kernel/sched/deadline.c
> >>+++ b/kernel/sched/deadline.c
> >>@@ -668,8 +668,11 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
> >> * Queueing this task back might have overloaded rq, check if we need
> >> * to kick someone away.
> >> */
> >>- if (has_pushable_dl_tasks(rq))
> >>+ if (has_pushable_dl_tasks(rq)) {
> >>+ lockdep_unpin_lock(&rq->lock);
> >> push_dl_task(rq);
> >>+ lockdep_pin_lock(&rq->lock);
> >>+ }
> >> #endif
> >>
> >> unlock:
> >>
> >>This removes the warning, but I am not sure if it is the correct fix (is it
> >>valid to unpin rq->lock, here?).
> >>
> >>If someone can confirm that this is the correct approach, I'll test the patch a
> >>little bit more and then I'll send a properly signed-off patch; otherwise, if
> >>someone can suggest the correct approach I'll try it.
Yes, its fine, although I would like a little comment with each unpin to
explain _why_ its fine.
So here its fine because nothing relies on rq->lock being held after
push_dl_task(), as the next thing we do is drop it anyway.
> >wake_up_new_task()
> > -> __task_rq_lock()
> > -> task_woken()
> > -> push_dl/rt_tasks()
> > -> push_dl/rt_task()
> >
> >I think you also should consider the lockdep pin_lock in this path.
Durr, clearly I overlooked both these when I did that. Sorry about that.
So how about:
---
Subject: sched: Add missing lockdep_unpin annotations
Luca and Wanpeng reported two missing annotations that led to false
lockdep complaints. Add the missing annotations.
Fixes: cbce1a686700 ("sched,lockdep: Employ lock pinning")
Reported-by: Luca Abeni <luca.abeni@unitn.it>
Reported-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/core.c | 9 ++++++++-
kernel/sched/deadline.c | 9 ++++++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1764a0f2a75b..81a74b76346c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2362,8 +2362,15 @@ void wake_up_new_task(struct task_struct *p)
trace_sched_wakeup_new(p);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
- if (p->sched_class->task_woken)
+ if (p->sched_class->task_woken) {
+ /*
+ * Nothing relies on rq->lock after this, so its fine to
+ * drop it.
+ */
+ lockdep_unpin_lock(&rq->lock);
p->sched_class->task_woken(rq, p);
+ lockdep_pin_lock(&rq->lock);
+ }
#endif
task_rq_unlock(rq, p, &flags);
}
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index fc8f01083527..cfdff233099b 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -668,8 +668,15 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
* Queueing this task back might have overloaded rq, check if we need
* to kick someone away.
*/
- if (has_pushable_dl_tasks(rq))
+ if (has_pushable_dl_tasks(rq)) {
+ /*
+ * Nothing relies on rq->lock after this, so its safe to drop
+ * rq->lock.
+ */
+ lockdep_unpin_lock(&rq->lock);
push_dl_task(rq);
+ lockdep_pin_lock(&rq->lock);
+ }
#endif
unlock:
^ permalink raw reply related [flat|nested] 6+ messages in thread* [tip:sched/urgent] sched/core: Add missing lockdep_unpin() annotations
2015-10-23 9:50 ` Peter Zijlstra
@ 2015-10-23 10:03 ` tip-bot for Peter Zijlstra
2015-10-23 20:10 ` lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq() Luca Abeni
1 sibling, 0 replies; 6+ messages in thread
From: tip-bot for Peter Zijlstra @ 2015-10-23 10:03 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, wanpeng.li, luca.abeni, tglx, mingo, peterz, hpa,
torvalds, efault, juri.lelli
Commit-ID: 0aaafaabfcba8aa991913cd3280a5dbf7f111a2a
Gitweb: http://git.kernel.org/tip/0aaafaabfcba8aa991913cd3280a5dbf7f111a2a
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Fri, 23 Oct 2015 11:50:08 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 23 Oct 2015 12:02:10 +0200
sched/core: Add missing lockdep_unpin() annotations
Luca and Wanpeng reported two missing annotations that led to
false lockdep complaints. Add the missing annotations.
Reported-by: Luca Abeni <luca.abeni@unitn.it>
Reported-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: cbce1a686700 ("sched,lockdep: Employ lock pinning")
Link: http://lkml.kernel.org/r/20151023095008.GY17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/core.c | 9 ++++++++-
kernel/sched/deadline.c | 9 ++++++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5bd7d60..bcd214e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2366,8 +2366,15 @@ void wake_up_new_task(struct task_struct *p)
trace_sched_wakeup_new(p);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
- if (p->sched_class->task_woken)
+ if (p->sched_class->task_woken) {
+ /*
+ * Nothing relies on rq->lock after this, so its fine to
+ * drop it.
+ */
+ lockdep_unpin_lock(&rq->lock);
p->sched_class->task_woken(rq, p);
+ lockdep_pin_lock(&rq->lock);
+ }
#endif
task_rq_unlock(rq, p, &flags);
}
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 142df26..8b0a15e 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -668,8 +668,15 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
* Queueing this task back might have overloaded rq, check if we need
* to kick someone away.
*/
- if (has_pushable_dl_tasks(rq))
+ if (has_pushable_dl_tasks(rq)) {
+ /*
+ * Nothing relies on rq->lock after this, so its safe to drop
+ * rq->lock.
+ */
+ lockdep_unpin_lock(&rq->lock);
push_dl_task(rq);
+ lockdep_pin_lock(&rq->lock);
+ }
#endif
unlock:
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq()
2015-10-23 9:50 ` Peter Zijlstra
2015-10-23 10:03 ` [tip:sched/urgent] sched/core: Add missing lockdep_unpin() annotations tip-bot for Peter Zijlstra
@ 2015-10-23 20:10 ` Luca Abeni
1 sibling, 0 replies; 6+ messages in thread
From: Luca Abeni @ 2015-10-23 20:10 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: Wanpeng Li, linux-kernel, Ingo Molnar, Juri Lelli
Hi Peter,
On Fri, 23 Oct 2015 11:50:08 +0200
Peter Zijlstra <peterz@infradead.org> wrote:
[...]
> > >>This removes the warning, but I am not sure if it is the correct
> > >>fix (is it valid to unpin rq->lock, here?).
> > >>
> > >>If someone can confirm that this is the correct approach, I'll
> > >>test the patch a little bit more and then I'll send a properly
> > >>signed-off patch; otherwise, if someone can suggest the correct
> > >>approach I'll try it.
>
> Yes, its fine, although I would like a little comment with each unpin
> to explain _why_ its fine.
>
> So here its fine because nothing relies on rq->lock being held after
> push_dl_task(), as the next thing we do is drop it anyway.
Thanks for explaining (now I see why it makes sense :), and thanks for
the patch!
I am using it locally, and everything is working fine.
Thanks,
Luca
>
> > >wake_up_new_task()
> > > -> __task_rq_lock()
> > > -> task_woken()
> > > -> push_dl/rt_tasks()
> > > -> push_dl/rt_task()
> > >
> > >I think you also should consider the lockdep pin_lock in this path.
>
> Durr, clearly I overlooked both these when I did that. Sorry about
> that.
>
> So how about:
>
> ---
> Subject: sched: Add missing lockdep_unpin annotations
>
> Luca and Wanpeng reported two missing annotations that led to false
> lockdep complaints. Add the missing annotations.
>
> Fixes: cbce1a686700 ("sched,lockdep: Employ lock pinning")
> Reported-by: Luca Abeni <luca.abeni@unitn.it>
> Reported-by: Wanpeng Li <wanpeng.li@hotmail.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> kernel/sched/core.c | 9 ++++++++-
> kernel/sched/deadline.c | 9 ++++++++-
> 2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 1764a0f2a75b..81a74b76346c 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2362,8 +2362,15 @@ void wake_up_new_task(struct task_struct *p)
> trace_sched_wakeup_new(p);
> check_preempt_curr(rq, p, WF_FORK);
> #ifdef CONFIG_SMP
> - if (p->sched_class->task_woken)
> + if (p->sched_class->task_woken) {
> + /*
> + * Nothing relies on rq->lock after this, so its
> fine to
> + * drop it.
> + */
> + lockdep_unpin_lock(&rq->lock);
> p->sched_class->task_woken(rq, p);
> + lockdep_pin_lock(&rq->lock);
> + }
> #endif
> task_rq_unlock(rq, p, &flags);
> }
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index fc8f01083527..cfdff233099b 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -668,8 +668,15 @@ static enum hrtimer_restart dl_task_timer(struct
> hrtimer *timer)
> * Queueing this task back might have overloaded rq, check
> if we need
> * to kick someone away.
> */
> - if (has_pushable_dl_tasks(rq))
> + if (has_pushable_dl_tasks(rq)) {
> + /*
> + * Nothing relies on rq->lock after this, so its
> safe to drop
> + * rq->lock.
> + */
> + lockdep_unpin_lock(&rq->lock);
> push_dl_task(rq);
> + lockdep_pin_lock(&rq->lock);
> + }
> #endif
>
> unlock:
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2015-10-23 20:10 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-10-21 13:20 lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq() Luca Abeni
2015-10-22 5:35 ` Wanpeng Li
2015-10-22 7:06 ` Luca Abeni
2015-10-23 9:50 ` Peter Zijlstra
2015-10-23 10:03 ` [tip:sched/urgent] sched/core: Add missing lockdep_unpin() annotations tip-bot for Peter Zijlstra
2015-10-23 20:10 ` lockdep-related warning in kernel/sched/deadline.c::find_lock_later_rq() Luca Abeni
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