From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Wed, 11 Feb 2015 23:25:32 +0000 (-0800)
Subject: mm/hugetlb: add migration entry check in __unmap_hugepage_range
X-Git-Tag: v3.4.108~145
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2a4edc62b38380cd464fc4b65524f626bf76fb1f;p=thirdparty%2Fkernel%2Fstable.git

mm/hugetlb: add migration entry check in __unmap_hugepage_range

commit 9fbc1f635fd0bd28cb32550211bf095753ac637a upstream.

If __unmap_hugepage_range() tries to unmap the address range over which
hugepage migration is on the way, we get the wrong page because pte_page()
doesn't work for migration entries.  This patch simply clears the pte for
migration entries as we do for hwpoison entries.

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>
[lizf: Backported to 3.4:
 - adjust context
 - update the comment that we doesn't clear pte here]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 5f12dba6d08ee..bc36e280ce8bd 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2401,9 +2401,10 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 			continue;
 
 		/*
-		 * HWPoisoned hugepage is already unmapped and dropped reference
+		 * Migrating hugepage or HWPoisoned hugepage is already
+		 * unmapped and its refcount is dropped
 		 */
-		if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
+		if (unlikely(!pte_present(pte)))
 			continue;
 
 		page = pte_page(pte);