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From: Johannes Weiner <>
To: Chris Down <>
Cc: Andrew Morton <>,
	Tejun Heo <>,,,,
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
Message-ID: <> (raw)
In-Reply-To: <>

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 <>
> Signed-off-by: Chris Down <>
> Cc: Andrew Morton <>
> Cc: Tejun Heo <>
> Cc:
> Cc:
> Cc:
> Cc:
> Cc: # 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 <>

      parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-12 18:02 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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