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From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Greg Thelen <gthelen@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	David Rientjes <rientjes@google.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Minchan Kim <minchan.kim@gmail.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] oom: handle overflow in mem_cgroup_out_of_memory()
Date: Wed, 26 Jan 2011 19:10:34 +0530	[thread overview]
Message-ID: <AANLkTikZwbmVr-jvOoyd0WZhfxtHvqK=n1B-zWLr3xDa@mail.gmail.com> (raw)
In-Reply-To: <1296030555-3594-1-git-send-email-gthelen@google.com>

On Wed, Jan 26, 2011 at 1:59 PM, Greg Thelen <gthelen@google.com> wrote:
> mem_cgroup_get_limit() returns a byte limit as a unsigned 64 bit value,
> which is converted to a page count by mem_cgroup_out_of_memory().  Prior
> to this patch the conversion could overflow on 32 bit platforms
> yielding a limit of zero.
>

Why would the overflow occur? Due to the right shift being used with
unsigned long long? I am afraid I don't have quick access to a 32 bit
box to test the patch. May be I too drained to understand the problem,
can you post the corresponding assembly for analysis?

Balbir

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  reply	other threads:[~2011-01-26 13:40 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-26  8:29 Greg Thelen
2011-01-26 13:40 ` Balbir Singh [this message]
2011-01-26 17:07 ` Johannes Weiner
2011-01-26 17:33   ` Greg Thelen
2011-01-26 18:30     ` Johannes Weiner
2011-01-26 20:32       ` Greg Thelen
2011-01-26 22:29         ` Andrew Morton
2011-01-27  0:24           ` KAMEZAWA Hiroyuki
2011-01-27  0:53             ` [BUGFIX] memcg: fix res_counter_read_u64 lock aware (Was " KAMEZAWA Hiroyuki
2011-01-27  1:08               ` Andrew Morton
2011-01-27  1:24                 ` KAMEZAWA Hiroyuki
2011-01-27  1:34                 ` KAMEZAWA Hiroyuki
2011-01-27  1:55                   ` Andrew Morton
2011-01-27  1:43               ` [BUGFIX v2] " KAMEZAWA Hiroyuki
2011-01-27  1:57                 ` Andrew Morton
2011-01-27  2:13                   ` KAMEZAWA Hiroyuki
2011-01-27  0:40     ` KAMEZAWA Hiroyuki

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