Re: [PATCH 2/3] kthread: Prevent deadlock when kthread_mod_delayed_work() races with kthread_cancel_delayed_work_sync()

[Andrew Morton]

On Fri, 11 Jun 2021 09:16:52 +0200 Petr Mladek <pmladek@xxxxxxxx> wrote:

> On Thu 2021-06-10 14:30:30, Andrew Morton wrote:
> > On Thu, 10 Jun 2021 15:30:50 +0200 Petr Mladek <pmladek@xxxxxxxx> wrote:
> > 
> > > The system might hang with the following backtrace:
> > 
> > Well that's not good.
> 
> Fortunately, the API users normally synchronize these operations
> another way. The race should never happen when the API is used
> a reasonable way,
> see https://lore.kernel.org/lkml/YKZLnTNOlUQ85F2s@alley/
> 
> > > Fixes: 9a6b06c8d9a220860468a ("kthread: allow to modify delayed kthread work")
> > > Reported-by: Martin Liu <liumartin@xxxxxxxxxx>
> > > Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
> > 
> > Was a -stable backport considered?
> 
> Good point! It would make sense to backport it. System hang is never
> good.
> 
> Could you please add Cc: stable@xxxxxxxxxxxxxxx or should I resend the
> patchset?

I made that change to patches 1&2.  I don't think patch 3 need be
backported?