From: Baoquan He <bhe@redhat.com>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Hui Su <sh_def@163.com>, Alex Shi <alex.shi@linux.alibaba.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm/memcontrol: fix warning in mem_cgroup_page_lruvec()
Date: Wed, 6 Jan 2021 14:49:35 +0800 [thread overview]
Message-ID: <20210106064935.GA3338@MiWiFi-R3L-srv> (raw)
In-Reply-To: <alpine.LSU.2.11.2101032056260.1093@eggly.anvils>
On 01/03/21 at 09:03pm, Hugh Dickins wrote:
> Boot a CONFIG_MEMCG=y kernel with "cgroup_disabled=memory" and you are
> met by a series of warnings from the VM_WARN_ON_ONCE_PAGE(!memcg, page)
> recently added to the inline mem_cgroup_page_lruvec().
>
> An earlier attempt to place that warning, in mem_cgroup_lruvec(), had
> been careful to do so after weeding out the mem_cgroup_disabled() case;
> but was itself invalid because of the mem_cgroup_lruvec(NULL, pgdat) in
> clear_pgdat_congested() and age_active_anon().
>
> Warning in mem_cgroup_page_lruvec() was once useful in detecting a KSM
> charge bug, so may be worth keeping: but skip if mem_cgroup_disabled().
>
> Fixes: 9a1ac2288cf1 ("mm/memcontrol:rewrite mem_cgroup_page_lruvec()")
> Signed-off-by: Hugh Dickins <hughd@google.com>
> ---
>
> include/linux/memcontrol.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- 5.11-rc2/include/linux/memcontrol.h 2020-12-27 20:39:36.751923135 -0800
> +++ linux/include/linux/memcontrol.h 2021-01-03 19:38:24.822978559 -0800
> @@ -665,7 +665,7 @@ static inline struct lruvec *mem_cgroup_
> {
> struct mem_cgroup *memcg = page_memcg(page);
>
> - VM_WARN_ON_ONCE_PAGE(!memcg, page);
> + VM_WARN_ON_ONCE_PAGE(!memcg && !mem_cgroup_disabled(), page);
> return mem_cgroup_lruvec(memcg, pgdat);
Thanks for fixing this. We also encountered this issue in kdump kernel
with the mainline 5.10 kernel since 'cgroup_disable=memory' is added.
Reviewed-by: Baoquan He <bhe@redhat.com>
next prev parent reply other threads:[~2021-01-06 6:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 5:03 [PATCH] mm/memcontrol: fix warning in mem_cgroup_page_lruvec() Hugh Dickins
2021-01-04 8:11 ` Alex Shi
2021-01-06 6:49 ` Baoquan He [this message]
2021-01-06 19:33 ` Andrew Morton
2021-01-06 19:35 ` Andrew Morton
2021-01-07 2:53 ` Baoquan He
2021-01-06 16:19 ` Chris Down
2021-01-07 18:04 ` Vlastimil Babka
2021-01-09 2:23 ` Hugh Dickins
[not found] <alpine.LSU.2.11.2101032107230.1158@eggly.anvils>
2021-01-04 18:09 ` Roman Gushchin
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