From: Qais Yousef <qais.yousef@arm.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
Abhijeet Dharmapurikar <adharmap@quicinc.com>,
Valentin Schneider <valentin.schneider@arm.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
"Steven Rostedt (Google)" <rostedt@goodmis.org>,
x86@kernel.org, stable@vger.kernel.org
Subject: Re: [tip: sched/core] sched/tracing: Don't re-read p->state when emitting sched_switch event
Date: Tue, 8 Mar 2022 18:51:38 +0000 [thread overview]
Message-ID: <20220308185138.ldxfqd242uxowymd@wubuntu> (raw)
In-Reply-To: <YiecMTy8ckUdXTQO@kroah.com>
On 03/08/22 19:10, Greg KH wrote:
> On Tue, Mar 08, 2022 at 06:02:40PM +0000, Qais Yousef wrote:
> > +CC stable
> >
> > On 03/01/22 15:24, tip-bot2 for Valentin Schneider wrote:
> > > The following commit has been merged into the sched/core branch of tip:
> > >
> > > Commit-ID: fa2c3254d7cfff5f7a916ab928a562d1165f17bb
> > > Gitweb: https://git.kernel.org/tip/fa2c3254d7cfff5f7a916ab928a562d1165f17bb
> > > Author: Valentin Schneider <valentin.schneider@arm.com>
> > > AuthorDate: Thu, 20 Jan 2022 16:25:19
> > > Committer: Peter Zijlstra <peterz@infradead.org>
> > > CommitterDate: Tue, 01 Mar 2022 16:18:39 +01:00
> > >
> > > sched/tracing: Don't re-read p->state when emitting sched_switch event
> > >
> > > As of commit
> > >
> > > c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu")
> > >
> > > the following sequence becomes possible:
> > >
> > > p->__state = TASK_INTERRUPTIBLE;
> > > __schedule()
> > > deactivate_task(p);
> > > ttwu()
> > > READ !p->on_rq
> > > p->__state=TASK_WAKING
> > > trace_sched_switch()
> > > __trace_sched_switch_state()
> > > task_state_index()
> > > return 0;
> > >
> > > TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in
> > > the trace event.
> > >
> > > Prevent this by pushing the value read from __schedule() down the trace
> > > event.
> > >
> > > Reported-by: Abhijeet Dharmapurikar <adharmap@quicinc.com>
> > > Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > > Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> > > Link: https://lore.kernel.org/r/20220120162520.570782-2-valentin.schneider@arm.com
> >
> > Any objection to picking this for stable? I'm interested in this one for some
> > Android users but prefer if it can be taken by stable rather than backport it
> > individually.
> >
> > I think it makes sense to pick the next one in the series too.
>
> What commit does this fix in Linus's tree?
It should be this one: c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu")
Not sure about the 2nd patch, but I can try to figure it out.
> Once it hits Linus's tree, let stable@vger.kernel.org know what the git
> commit id is in Linus's tree.
Sure. My bad if I rushed the request. I just wanted to know whether it's okay
for this to go into stable. If no one shouts, I'll ping once it lands in
Linus'.
Thanks!
--
Qais Yousef
next prev parent reply other threads:[~2022-03-08 18:53 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-20 16:25 [PATCH v3 0/2] sched/tracing: sched_switch prev_state reported as TASK_RUNNING when it's not Valentin Schneider
2022-01-20 16:25 ` [PATCH v3 1/2] sched/tracing: Don't re-read p->state when emitting sched_switch event Valentin Schneider
2022-03-01 15:24 ` [tip: sched/core] " tip-bot2 for Valentin Schneider
2022-03-04 16:13 ` Valentin Schneider
2022-03-08 18:02 ` Qais Yousef
2022-03-08 18:10 ` Greg KH
2022-03-08 18:51 ` Qais Yousef [this message]
2022-04-09 23:38 ` Qais Yousef
2022-04-10 22:06 ` Qais Yousef
2022-04-10 23:22 ` Holger Hoffstätte
2022-04-11 7:18 ` Holger Hoffstätte
2022-04-11 7:28 ` Greg KH
2022-04-11 8:05 ` Holger Hoffstätte
2022-04-11 13:23 ` Greg KH
2022-04-11 13:22 ` Greg KH
2022-04-11 21:06 ` Qais Yousef
2022-01-20 16:25 ` [PATCH v3 2/2] sched/tracing: Report TASK_RTLOCK_WAIT tasks as TASK_UNINTERRUPTIBLE Valentin Schneider
2022-03-01 15:24 ` [tip: sched/core] " tip-bot2 for Valentin Schneider
2022-04-09 23:42 ` [PATCH v3 2/2] " Qais Yousef
2022-04-10 6:14 ` Greg KH
2022-04-10 22:13 ` Qais Yousef
2022-04-11 13:20 ` Greg KH
2022-04-11 20:18 ` Qais Yousef
2022-01-21 17:15 ` [PATCH v3 0/2] sched/tracing: sched_switch prev_state reported as TASK_RUNNING when it's not Steven Rostedt
2022-02-27 15:33 ` Peter Zijlstra
2022-04-21 22:12 ` [PATCH] sched/tracing: append prev_state to tp args instead Delyan Kratunov
2022-04-22 10:13 ` Valentin Schneider
2022-04-22 11:09 ` Peter Zijlstra
2022-04-22 15:55 ` Steven Rostedt
2022-04-22 16:54 ` Andrii Nakryiko
2022-04-22 16:37 ` Andrii Nakryiko
2022-04-22 17:22 ` Delyan Kratunov
2022-04-22 18:30 ` Alexei Starovoitov
2022-04-26 12:28 ` Peter Zijlstra
2022-04-26 14:09 ` Qais Yousef
2022-04-26 15:54 ` Andrii Nakryiko
2022-04-27 10:34 ` Qais Yousef
2022-04-27 18:17 ` Andrii Nakryiko
2022-04-27 20:32 ` Alexei Starovoitov
2022-04-28 10:02 ` Qais Yousef
2022-05-09 19:32 ` Andrii Nakryiko
2022-05-10 7:01 ` Peter Zijlstra
2022-05-10 8:29 ` Peter Zijlstra
2022-05-10 14:31 ` Steven Rostedt
2022-05-11 18:28 ` [PATCH v2] " Delyan Kratunov
2022-05-11 19:10 ` Steven Rostedt
2022-05-11 22:45 ` [tip: sched/urgent] sched/tracing: Append " tip-bot2 for Delyan Kratunov
2022-05-11 23:40 ` [PATCH v2] sched/tracing: append " Thomas Gleixner
2022-04-26 15:51 ` [PATCH] " Andrii Nakryiko
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