From: Shakeel Butt <shakeel.butt@linux.dev>
To: "T.J. Mercier" <tjmercier@google.com>
Cc: Michal Hocko <mhocko@suse.com>,
hannes@cmpxchg.org, roman.gushchin@linux.dev,
muchun.song@linux.dev, zhengqi.arch@bytedance.com,
akpm@linux-foundation.org, cgroups@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] mm: memcontrol: fix NULL pointer deref in high_work_func() on dying memcg
Date: Tue, 27 Oct 2026 11:07:13 -0700 [thread overview]
Message-ID: <auDno4JDDyhV1Y4Q@linux.dev> (raw)
In-Reply-To: <CABdmKX2Hua321nr9vR=Q7-Uu5N6e2JARtUe5RnC3JFu6aGRqhQ@mail.gmail.com>
On Tue, Oct 27, 2026 at 10:28:22AM -0700, T.J. Mercier wrote:
> On Tue, Oct 27, 2026 at 2:41 AM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Mon 26-10-26 11:01:51, T.J. Mercier wrote:
> > > On Mon, Oct 26, 2026 at 6:25 AM Michal Hocko <mhocko@suse.com> wrote:
> > > >
[...]
> > > > On Fri 23-10-26 15:23:13, T.J. Mercier wrote:
> > I must be missing something really obvious here because I really do not
> > follow you here too. So we are offlining a memcg. We need to coordinate
> > memory reclaim with the memcg tear down, right? For the high reclaim we
> > can achieve this synchronization through disable_work_sync in
> > mem_cgroup_css_offline.
>
> We could call disable_work_sync() in mem_cgroup_css_offline(), but
> that waits until high_work_func() is done and it could be performing
> reclaim. mem_cgroup_css_offline() runs under the cgroup_mutex, and
> cgroup_mutex contention is already bad enough. I don't want to add to
> it. It would also block the rest of the cgroup_offline_wq.
+1, let's not add more potential contention sources for cgroup_mutex.
next prev parent reply other threads:[~2026-10-27 18:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-23 22:23 T.J. Mercier
2026-10-26 13:25 ` Michal Hocko
2026-10-26 18:01 ` T.J. Mercier
2026-10-27 9:40 ` Michal Hocko
2026-10-27 17:28 ` T.J. Mercier
2026-10-27 18:07 ` Shakeel Butt [this message]
2026-10-27 2:42 ` Muchun Song
2026-10-27 17:42 ` T.J. Mercier
2026-10-27 23:11 ` T.J. Mercier
2026-10-28 2:45 ` Muchun Song
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