From: Hugh Dickins <hughd@google.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Hugh Dickins <hughd@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Michal Hocko <mhocko@suse.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, 30 Nov 2022 09:36:15 -0800 (PST) [thread overview]
Message-ID: <e0918c92-90cd-e3ed-f4e6-92d02062c252@google.com> (raw)
In-Reply-To: <CALvZod7_FjO-CjzHUpQTsCTm4-68a1eKi_qY=4XdF+g7yMLd4Q@mail.gmail.com>
On Wed, 30 Nov 2022, Shakeel Butt wrote:
>
> 2. For 6.2 (or 6.3), remove the non-present pte migration with some
> additional text in the warning and do the rmap cleanup.
I just had an idea for softening the impact of that change: a moment's
more thought may prove it's a terrible idea, but right now I like it.
What if we keep the non-present pte migration throughout the deprecation
period, but with a change to the where the folio_trylock() is done, and
a refusal to move the charge on the page of a non-present pte, if that
page/folio is currently mapped anywhere else - the folio lock preventing
it from then becoming mapped while in mem_cgroup_move_account().
There's an argument that that's a better implementation anyway: that
we should not interfere with others' pages; but perhaps it would turn
out to be unimplementable, or would make for less predictable behaviour.
Hugh
next prev parent reply other threads:[~2022-11-30 17:36 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
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 [this message]
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
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