From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Wed, 11 Feb 2015 23:25:28 +0000 (-0800)
Subject: mm/hugetlb: add migration/hwpoisoned entry check in hugetlb_change_protection
X-Git-Tag: v3.2.69~185
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9e725572445374fe05d80478f4c4ff9631f9a59c;p=pandora-kernel.git

mm/hugetlb: add migration/hwpoisoned entry check in hugetlb_change_protection

commit a8bda28d87c38c6aa93de28ba5d30cc18e865a11 upstream.

There is a race condition between hugepage migration and
change_protection(), where hugetlb_change_protection() doesn't care about
migration entries and wrongly overwrites them.  That causes unexpected
results like kernel crash.  HWPoison entries also can cause the same
problem.

This patch adds is_hugetlb_entry_(migration|hwpoisoned) check in this
function to do proper actions.

Fixes: 290408d4a2 ("hugetlb: hugepage migration core")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Steve Capper <steve.capper@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2:
 - Adjust context
 - We don't have split page table locks, so don't unlock inside the loop
 - We don't count pages here]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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