From: Johannes Weiner <hannes@cmpxchg.org>
To: Greg Thelen <gthelen@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
Wu Fengguang <fengguang.wu@intel.com>,
Minchan Kim <minchan.kim@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages()
Date: Tue, 9 Nov 2010 10:10:06 +0100 [thread overview]
Message-ID: <20101109091006.GR23393@cmpxchg.org> (raw)
In-Reply-To: <1289292853-7022-1-git-send-email-gthelen@google.com>
On Tue, Nov 09, 2010 at 12:54:13AM -0800, Greg Thelen wrote:
> memcg limit and usage values are stored in res_counter, as 64-bit
> numbers, even on 32-bit machines. The "free" variable in
> memcg_hierarchical_free_pages() stores the difference between two
> 64-bit numbers (limit - current_usage), and thus should be stored
> in a 64-bit local rather than a machine defined unsigned long.
It is converted to pages before the assignment, but even that might
overflow on 32-bit if the difference is sufficiently large (> 1<<44).
> Reported-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> Signed-off-by: Greg Thelen <gthelen@google.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Greg Thelen <gthelen@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
Wu Fengguang <fengguang.wu@intel.com>,
Minchan Kim <minchan.kim@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages()
Date: Tue, 9 Nov 2010 10:10:06 +0100 [thread overview]
Message-ID: <20101109091006.GR23393@cmpxchg.org> (raw)
In-Reply-To: <1289292853-7022-1-git-send-email-gthelen@google.com>
On Tue, Nov 09, 2010 at 12:54:13AM -0800, Greg Thelen wrote:
> memcg limit and usage values are stored in res_counter, as 64-bit
> numbers, even on 32-bit machines. The "free" variable in
> memcg_hierarchical_free_pages() stores the difference between two
> 64-bit numbers (limit - current_usage), and thus should be stored
> in a 64-bit local rather than a machine defined unsigned long.
It is converted to pages before the assignment, but even that might
overflow on 32-bit if the difference is sufficiently large (> 1<<44).
> Reported-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> Signed-off-by: Greg Thelen <gthelen@google.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
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next prev parent reply other threads:[~2010-11-09 9:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-09 8:54 [PATCH] memcg: avoid "free" overflow in memcg_hierarchical_free_pages() Greg Thelen
2010-11-09 8:54 ` Greg Thelen
2010-11-09 9:10 ` Johannes Weiner [this message]
2010-11-09 9:10 ` Johannes Weiner
2010-11-16 3:47 ` KAMEZAWA Hiroyuki
2010-11-16 3:47 ` KAMEZAWA Hiroyuki
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