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References: <alpine.DEB.2.02.1311121811310.29891@chino.kir.corp.google.com> <20131120141534.06ea091ca53b1dec60ace63d@linux-foundation.org>
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Sat, 23 Nov 2013 15:49:08 -0500
Message-ID: <CAHGf_=ooNHx=2HeUDGxrZFma-6YRvL42ViDMkSOqLOffk8MVsw@mail.gmail.com>
Subject: Re: [patch -mm] mm, mempolicy: silence gcc warning
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Sender: owner-linux-mm@kvack.org
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To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>, Fengguang Wu <fengguang.wu@intel.com>, Kees Cook <keescook@chromium.org>, Rik van Riel <riel@redhat.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>

>> --- a/mm/mempolicy.c
>> +++ b/mm/mempolicy.c
>> @@ -2950,7 +2950,7 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
>>               return;
>>       }
>>
>> -     p += snprintf(p, maxlen, policy_modes[mode]);
>> +     p += snprintf(p, maxlen, "%s", policy_modes[mode]);
>>
>>       if (flags & MPOL_MODE_FLAGS) {
>>               p += snprintf(p, buffer + maxlen - p, "=");
>
> mutter.  There are no '%'s in policy_modes[].  Maybe we should only do
> this #ifdef CONFIG_KEES.
>
> mpol_to_str() would be simpler (and slower) if it was switched to use
> strncat().

IMHO, you should queue this patch. mpol_to_str() is not fast path at all and
I don't want worry about false positive warning.

> It worries me that the CONFIG_NUMA=n version of mpol_to_str() doesn't
> stick a '\0' into *buffer.  Hopefully it never gets called...

Don't worry. It never happens. Currently, all of caller depend on CONFIG_NUMA.
However it would be nice if CONFIG_NUMA=n version of mpol_to_str() is
implemented
more carefully. I don't know who's mistake.

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