On Tue, Mar 3, 2020 at 10:40 AM Naresh Kamboju
<naresh.kamboju@xxxxxxxxxx> wrote:
>
> On Tue, 3 Mar 2020 at 23:17, Yang Shi <shy828301@xxxxxxxxx> wrote:
> >
> > On Tue, Mar 3, 2020 at 2:53 AM Tetsuo Handa
> > <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > Hello, Naresh.
> > >
> > > > [ 98.003346] WARNING: CPU: 2 PID: 340 at
> > > > include/linux/sched/mm.h:323 alloc_page_buffers+0x210/0x288
> <Trim>
> > >
> > Could you please try the below debug patch? This is not the proper
> > fix, but it may help us narrow down the problem.
> >
> > diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
> > index c49257a..1cc1cdc 100644
> > --- a/include/linux/sched/mm.h
> > +++ b/include/linux/sched/mm.h
> > @@ -320,6 +320,10 @@ static inline void
> > memalloc_nocma_restore(unsigned int flags)
> > */
> > static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
> > {
> > + if ((current->flags & PF_KTHREAD) &&
> > + current->active_memcg)
> > + return;
> > +
> > WARN_ON_ONCE(current->active_memcg);
> > current->active_memcg = memcg;
> > }
>
> After applying this patch the reported "warning" did not happen.
> Here is the full test log.
> https://lkft.validation.linaro.org/scheduler/job/1265325#L1287
Thanks for doing testing. We could confirm this is caused by
paralleled memalloc_use_memcg().
>
> - Naresh
