From: David Rientjes <rientjes@google.com>
To: Ryota Ozaki <ozaki.ryota@gmail.com>
Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman <gregkh@suse.de>,
linux-mm@kvack.org, stable@kernel.org
Subject: Re: [PATCH][RESEND] mm: Fix off-by-one bug in print_nodes_state
Date: Sun, 18 Dec 2011 14:44:24 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.00.1112181439500.1364@chino.kir.corp.google.com> (raw)
In-Reply-To: <1324209529-15892-1-git-send-email-ozaki.ryota@gmail.com>
On Sun, 18 Dec 2011, Ryota Ozaki wrote:
> /sys/devices/system/node/{online,possible} involve a garbage byte
> because print_nodes_state returns content size + 1. To fix the bug,
> the patch changes the use of cpuset_sprintf_cpulist to follow the
> use at other places, which is clearer and safer.
>
It's not a garbage byte, sysdev files use a buffer created with
get_zeroed_page(), so extra byte is guaranteed to be zero since
nodelist_scnprintf() won't write to it. So the issue here is that
print_nodes_state() returns a size that is off by one according to
ISO C99 although it won't cause a problem in practice.
> This bug was introduced since v2.6.24.
>
It's not a bug, the result of a 4-node system would be "0-3\n\0" and
returns 5 correctly. You can verify this very simply with strace.
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next prev parent reply other threads:[~2011-12-18 22:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-18 11:58 Ryota Ozaki
2011-12-18 21:28 ` KOSAKI Motohiro
2011-12-20 4:22 ` Ryota Ozaki
2011-12-18 22:44 ` David Rientjes [this message]
2011-12-18 22:48 ` KOSAKI Motohiro
2011-12-19 20:53 ` David Rientjes
2011-12-19 21:15 ` KOSAKI Motohiro
2011-12-20 4:43 ` Ryota Ozaki
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