From: Shakeel Butt <shakeelb@google.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: remove lock_page_memcg() from rmap
Date: Wed, 23 Nov 2022 10:34:27 -0800 [thread overview]
Message-ID: <CALvZod488YStQ5tucPgc0b3FSwiqFhVJptPceFvaZjj2Ba24YA@mail.gmail.com> (raw)
In-Reply-To: <20221123181838.1373440-1-hannes@cmpxchg.org>
On Wed, Nov 23, 2022 at 10:18 AM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> rmap changes (mapping and unmapping) of a page currently take
> lock_page_memcg() to serialize 1) update of the mapcount and the
> cgroup mapped counter with 2) cgroup moving the page and updating the
> old cgroup and the new cgroup counters based on page_mapped().
>
> Before b2052564e66d ("mm: memcontrol: continue cache reclaim from
> offlined groups"), we used to reassign all pages that could be found
> on a cgroup's LRU list on deletion - something that rmap didn't
> naturally serialize against. Since that commit, however, the only
> pages that get moved are those mapped into page tables of a task
> that's being migrated. In that case, the pte lock is always held (and
> we know the page is mapped), which keeps rmap changes at bay already.
>
> The additional lock_page_memcg() by rmap is redundant. Remove it.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
next prev parent reply other threads:[~2022-11-23 18:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-23 18:18 [PATCH] mm: remove lock_page_memcg() from rmap Johannes Weiner
2022-11-23 18:34 ` Shakeel Butt [this message]
2022-11-24 6:03 ` Hugh Dickins
2022-11-28 16:59 ` Johannes Weiner
2022-11-29 19:08 ` Johannes Weiner
2022-11-29 19:23 ` Linus Torvalds
2022-11-29 19:42 ` Shakeel Butt
2022-11-30 7:33 ` Hugh Dickins
2022-11-30 16:42 ` Shakeel Butt
2022-11-30 17:36 ` Hugh Dickins
2022-11-30 22:30 ` Johannes Weiner
2022-12-01 0:13 ` Hugh Dickins
2022-12-01 15:52 ` Johannes Weiner
2022-12-01 19:28 ` Hugh Dickins
2022-11-30 12:50 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CALvZod488YStQ5tucPgc0b3FSwiqFhVJptPceFvaZjj2Ba24YA@mail.gmail.com \
--to=shakeelb@google.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).