Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [tip: sched/core] sched/tracing: Don't re-read p->state when emitting sched_switch event | Date | Fri, 04 Mar 2022 16:13:04 +0000 |
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On 01/03/22 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
So I wasn't sure if that would be considered a "bug", but folks are asking for this to be backported; do we want to slap
Fixes: c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu")
to it?
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