From: Johannes Weiner <hannes@cmpxchg.org>
To: Chris Down <chris@chrisdown.name>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 1/2] mm, memcg: Fix corruption on 64-bit divisor in memory.high throttling
Date: Mon, 16 Mar 2020 12:19:07 -0400 [thread overview]
Message-ID: <20200316161907.GE67986@cmpxchg.org> (raw)
In-Reply-To: <80780887060514967d414b3cd91f9a316a16ab98.1584036142.git.chris@chrisdown.name>
On Thu, Mar 12, 2020 at 06:02:54PM +0000, Chris Down wrote:
> 0e4b01df8659 had a bunch of fixups to use the right division method.
> However, it seems that after all that it still wasn't right -- div_u64
> takes a 32-bit divisor.
>
> The headroom is still large (2^32 pages), so on mundane systems you
> won't hit this, but this should definitely be fixed.
>
> Fixes: 0e4b01df8659 ("mm, memcg: throttle allocators when failing reclaim over memory.high")
> Reported-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Chris Down <chris@chrisdown.name>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: linux-mm@kvack.org
> Cc: cgroups@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: kernel-team@fb.com
> Cc: stable@vger.kernel.org # 5.4.x
div_u64 versus div64_u64 is really a handgrenade. We just fixed a
bunch of those in psi as well.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
prev parent reply other threads:[~2020-03-16 16:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 18:02 [PATCH 1/2] mm, memcg: Fix corruption on 64-bit divisor in memory.high throttling Chris Down
2020-03-12 18:03 ` [PATCH 2/2] mm, memcg: Throttle allocators based on ancestral memory.high Chris Down
2020-03-16 16:21 ` Johannes Weiner
2020-03-16 16:19 ` Johannes Weiner [this message]
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