On 03/08/22 18:51, Qais Yousef wrote:
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")
Should this be okay to be picked up by stable now? I can see AUTOSEL has picked it up for v5.15+, but it impacts v5.10 too.
Thanks!
-- Qais Yousef