From: Shakeel Butt <shakeelb@google.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@suse.com>,
Linux MM <linux-mm@kvack.org>, Cgroups <cgroups@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH 1/2] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
Date: Fri, 19 Mar 2021 07:00:24 -0700 [thread overview]
Message-ID: <CALvZod4RD6ALiQHrFBMWMytYW0Lg+RFZapKKSWJbK+-ue9BG2A@mail.gmail.com> (raw)
In-Reply-To: <20210319054944.50048-1-hannes@cmpxchg.org>
On Thu, Mar 18, 2021 at 10:49 PM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> Since commit 2d1c498072de ("mm: memcontrol: make swap tracking an
> integral part of memory control"), the cgroup swap arrays are used to
> track memory ownership at the time of swap readahead and swapoff, even
> if swap space *accounting* has been turned off by the user via
> swapaccount=0 (which sets cgroup_memory_noswap).
>
> However, the patch was overzealous: by simply dropping the
> cgroup_memory_noswap conditionals in the swapon, swapoff and uncharge
> path, it caused the cgroup arrays being allocated even when the memory
> controller as a whole is disabled. This is a waste of that memory.
>
> Restore mem_cgroup_disabled() checks, implied previously by
> cgroup_memory_noswap, in the swapon, swapoff, and swap_entry_free
> callbacks.
>
> Fixes: 2d1c498072de ("mm: memcontrol: make swap tracking an integral part of memory control")
> Reported-by: Hugh Dickins <hughd@google.com>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
next prev parent reply other threads:[~2021-03-19 14:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 5:49 [PATCH 1/2] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled Johannes Weiner
2021-03-19 5:49 ` [PATCH 2/2] mm: memcontrol: deprecate swapaccounting=0 mode Johannes Weiner
2021-03-19 13:49 ` Shakeel Butt
2021-03-19 17:36 ` Johannes Weiner
2021-03-19 18:20 ` Shakeel Butt
2021-03-20 0:37 ` Hugh Dickins
2021-03-22 15:53 ` Johannes Weiner
2021-03-19 14:00 ` Shakeel Butt [this message]
2021-03-19 23:33 ` [PATCH 1/2] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled Hugh Dickins
2021-03-22 9:41 ` Michal Hocko
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