From: Shakeel Butt <shakeelb@google.com>
To: Roman Gushchin <guro@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Waiman Long <longman@redhat.com>
Subject: Re: [PATCH v6 01/10] mm: add missing smp read barrier on getting memcg kmem_cache pointer
Date: Wed, 5 Jun 2019 12:51:14 -0700 [thread overview]
Message-ID: <CALvZod6Cu+Uyy-Jp-er0Kz9dwLhmb5KO0XP3X55PVcSx4A4w3g@mail.gmail.com> (raw)
In-Reply-To: <20190605171355.GA10098@tower.DHCP.thefacebook.com>
On Wed, Jun 5, 2019 at 10:14 AM Roman Gushchin <guro@fb.com> wrote:
>
> On Tue, Jun 04, 2019 at 09:35:02PM -0700, Shakeel Butt wrote:
> > On Tue, Jun 4, 2019 at 7:45 PM Roman Gushchin <guro@fb.com> wrote:
> > >
> > > Johannes noticed that reading the memcg kmem_cache pointer in
> > > cache_from_memcg_idx() is performed using READ_ONCE() macro,
> > > which doesn't implement a SMP barrier, which is required
> > > by the logic.
> > >
> > > Add a proper smp_rmb() to be paired with smp_wmb() in
> > > memcg_create_kmem_cache().
> > >
> > > The same applies to memcg_create_kmem_cache() itself,
> > > which reads the same value without barriers and READ_ONCE().
> > >
> > > Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
> > > Signed-off-by: Roman Gushchin <guro@fb.com>
> >
> > Reviewed-by: Shakeel Butt <shakeelb@google.com>
> >
> > This seems like independent to the series. Shouldn't this be Cc'ed stable?
>
> It is independent, but let's keep it here to avoid merge conflicts.
>
> It has been so for a long time, and nobody complained, so I'm not sure
> if we really need a stable backport. Do you have a different opinion?
>
Nah, it's fine as it is.
next prev parent reply other threads:[~2019-06-05 19:51 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 2:44 [PATCH v6 00/10] mm: reparent slab memory on cgroup removal Roman Gushchin
2019-06-05 2:44 ` [PATCH v6 01/10] mm: add missing smp read barrier on getting memcg kmem_cache pointer Roman Gushchin
2019-06-05 4:35 ` Shakeel Butt
2019-06-05 17:14 ` Roman Gushchin
2019-06-05 19:51 ` Shakeel Butt [this message]
2019-06-05 16:42 ` Johannes Weiner
2019-06-09 12:10 ` Vladimir Davydov
2019-06-10 20:33 ` Johannes Weiner
2019-06-10 20:38 ` Roman Gushchin
2019-06-05 2:44 ` [PATCH v6 02/10] mm: postpone kmem_cache memcg pointer initialization to memcg_link_cache() Roman Gushchin
2019-06-05 2:44 ` [PATCH v6 03/10] mm: rename slab delayed deactivation functions and fields Roman Gushchin
2019-06-09 12:13 ` Vladimir Davydov
2019-06-05 2:44 ` [PATCH v6 04/10] mm: generalize postponed non-root kmem_cache deactivation Roman Gushchin
2019-06-09 12:23 ` Vladimir Davydov
2019-06-05 2:44 ` [PATCH v6 05/10] mm: introduce __memcg_kmem_uncharge_memcg() Roman Gushchin
2019-06-09 12:29 ` Vladimir Davydov
2019-06-05 2:44 ` [PATCH v6 06/10] mm: unify SLAB and SLUB page accounting Roman Gushchin
2019-06-05 2:44 ` [PATCH v6 07/10] mm: synchronize access to kmem_cache dying flag using a spinlock Roman Gushchin
2019-06-05 16:56 ` Johannes Weiner
2019-06-05 22:02 ` Roman Gushchin
2019-06-06 0:48 ` Roman Gushchin
2019-06-09 14:31 ` Vladimir Davydov
2019-06-10 20:46 ` Roman Gushchin
2019-06-05 2:44 ` [PATCH v6 08/10] mm: rework non-root kmem_cache lifecycle management Roman Gushchin
2019-06-09 17:09 ` Vladimir Davydov
2019-06-05 2:44 ` [PATCH v6 09/10] mm: stop setting page->mem_cgroup pointer for slab pages Roman Gushchin
2019-06-09 17:09 ` Vladimir Davydov
2019-06-05 2:44 ` [PATCH v6 10/10] mm: reparent slab memory on cgroup removal Roman Gushchin
2019-06-09 17:18 ` Vladimir Davydov
2019-06-05 4:14 ` [PATCH v6 00/10] " Andrew Morton
2019-06-05 20:45 ` Roman Gushchin
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