From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Date: Wed, 6 Aug 2014 23:08:05 +0000 (-0700)
Subject: mm: close race between do_fault_around() and fault_around_bytes_set()
X-Git-Tag: cleanup-for-v3.18~96^2~95
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aecd6f44266c13b8709245b21ded2d19291ab070;p=pandora-kernel.git

mm: close race between do_fault_around() and fault_around_bytes_set()

Things can go wrong if fault_around_bytes will be changed under
do_fault_around(): between fault_around_mask() and fault_around_pages().

Let's read fault_around_bytes only once during do_fault_around() and
calculate mask based on the reading.

Note: fault_around_bytes can only be updated via debug interface.  Also
I've tried but was not able to trigger a bad behaviour without the
patch.  So I would not consider this patch as urgent.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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