On Thu, Jul 23, 2020 at 10:11:28PM +0200, Peter Zijlstra wrote:
> On Thu, Jul 23, 2020 at 08:41:03PM +0100, Chris Wilson wrote:
>
> > I am very sorry for the wild goose chase.
>
> *phew*... all good then. I was starting to go a little ga-ga trying to
> make sense of things.
>
> Arguably we
On Thu, Jul 23, 2020 at 08:41:03PM +0100, Chris Wilson wrote:
> I am very sorry for the wild goose chase.
*phew*... all good then. I was starting to go a little ga-ga trying to
make sense of things.
Arguably we should probably do something like:
@@ -4555,7 +4572,7 @@ asmlinkage __visible void
Quoting Peter Zijlstra (2020-07-23 19:28:41)
> On Wed, Jul 22, 2020 at 10:57:56AM +0100, Chris Wilson wrote:
>
> > Perhaps more damning is that I can replace WF_ON_CPU with p->on_cpu to
> > suppress the warning:
>
> *argh*, I'm starting to go mad...
>
> Chris, could you please try the below
On Wed, Jul 22, 2020 at 10:57:56AM +0100, Chris Wilson wrote:
> Perhaps more damning is that I can replace WF_ON_CPU with p->on_cpu to
> suppress the warning:
*argh*, I'm starting to go mad...
Chris, could you please try the below patch?
Can you also confirm that if you do:
$ echo
Quoting pet...@infradead.org (2020-07-21 12:37:19)
> On Tue, Jul 21, 2020 at 11:49:05AM +0100, Chris Wilson wrote:
> > Quoting Peter Zijlstra (2020-06-22 11:01:23)
> > > @@ -2378,6 +2385,9 @@ static inline bool ttwu_queue_cond(int c
> > > static bool ttwu_queue_wakelist(struct task_struct *p, int
On Tue, Jul 21, 2020 at 11:49:05AM +0100, Chris Wilson wrote:
> Quoting Peter Zijlstra (2020-06-22 11:01:23)
> > @@ -2378,6 +2385,9 @@ static inline bool ttwu_queue_cond(int c
> > static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int
> > wake_flags)
> > {
> > if
Quoting Peter Zijlstra (2020-06-22 11:01:23)
> @@ -2378,6 +2385,9 @@ static inline bool ttwu_queue_cond(int c
> static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int
> wake_flags)
> {
> if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
> + if
*sigh*, this one should actually build and I got a smatch report that
there's an uninitizlied usage of @cpu, so I shuffled that around a bit.
---
Subject: sched: Fix ttwu() race
From: Peter Zijlstra
Date: Mon, 22 Jun 2020 12:01:23 +0200
Paul reported rcutorture occasionally hitting a NULL
Paul reported rcutorture occasionally hitting a NULL deref:
sched_ttwu_pending()
ttwu_do_wakeup()
check_preempt_curr() := check_preempt_wakeup()
find_matching_se()
is_same_group()
if (se->cfs_rq == pse->cfs_rq) <-- *BOOM*
Debugging showed that this only
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