Re: [PATCH 0/2] freezer,sched: do not restore saved_state of a thawed task

[Aiqun(Maria) Yu]

On 11/21/2023 1:36 AM, Elliot Berman wrote:
> This series applies couple fixes to commit 8f0eed4a78a8 ("freezer,sched:
> Use saved_state to reduce some spurious wakeups") which was found while
> testing with legacy cgroup freezer. My original testing was only with
> system-wide freezer. We found that thaw_task could be called on a task
> which was already frozen. Prior to commit 8f0eed4a78a8 ("freezer,sched:
> Use saved_state to reduce some spurious wakeups"), this wasn't an issue
> as kernel would try to wake up TASK_FROZEN, which wouldn't match the
> thawed task state, and no harm done to task. After commit 8f0eed4a78a8
> ("freezer,sched: Use saved_state to reduce some spurious wakeups"), it
> was possible to overwrite the state of thawed task.
>
> To: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> To: Pavel Machek <pavel@xxxxxx>
> To: Ingo Molnar <mingo@xxxxxxxxxx>
> To: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Cc:  <linux-arm-msm@xxxxxxxxxxxxxxx>
> Cc: Pavan Kondeti <quic_pkondeti@xxxxxxxxxxx>
> Cc: Aiqun Yu (Maria) <quic_aiquny@xxxxxxxxxxx>
> Cc:  <linux-pm@xxxxxxxxxxxxxxx>
> Cc:  <linux-kernel@xxxxxxxxxxxxxxx>
> Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
Shall we add Fixed tag and Cc: stable@xxxxxxxxxxxxxxx ?
Since it is fixing a stable user thread hung issue.
> Originally sent to only linux-arm-msm, resending to correct authors.
> - Link to v1: https://lore.kernel.org/r/20231120-freezer-state-multiple-thaws-v1-0-a4c453f50745@xxxxxxxxxxx
>
> ---
> Elliot Berman (2):
>        freezer,sched: do not restore saved_state of a thawed task
>        freezer,sched: clean saved_state when restoring it during thaw
>
>   kernel/freezer.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> ---
> base-commit: 6d7e4782bcf549221b4ccfffec2cf4d1a473f1a3
> change-id: 20231108-freezer-state-multiple-thaws-7a3a8d9dadb3
>
> Best regards,

--
Thx and BRs,
Aiqun(Maria) Yu