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authorJohannes Weiner <hannes@cmpxchg.org>2011-01-20 14:44:18 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-20 17:02:05 -0800
commit453c719261c0b4030b2676124adb6e81c5fb6833 (patch)
treea90af16797ccb11133046fccdeb52725e2f09167 /mm
parent6a108a14fa356ef607be308b68337939e56ea94e (diff)
downloadlinux-linaro-stable-453c719261c0b4030b2676124adb6e81c5fb6833.tar.gz
thp: keep highpte mapped until it is no longer needed
Two users reported THP-related crashes on 32-bit x86 machines. Their oops reports indicated an invalid pte, and subsequent code inspection showed that the highpte is actually used after unmap. The fix is to unmap the pte only after all operations against it are finished. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Ilya Dryomov <idryomov@gmail.com> Reported-by: werner <w.landgraf@ru.ru> Cc: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Ilya Dryomov <idryomov@gmail.com> Tested-by: Steven Rostedt <rostedt@goodmis.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/huge_memory.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 004c9c2aac78..c4f634b3a48e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1837,9 +1837,9 @@ static void collapse_huge_page(struct mm_struct *mm,
spin_lock(ptl);
isolated = __collapse_huge_page_isolate(vma, address, pte);
spin_unlock(ptl);
- pte_unmap(pte);
if (unlikely(!isolated)) {
+ pte_unmap(pte);
spin_lock(&mm->page_table_lock);
BUG_ON(!pmd_none(*pmd));
set_pmd_at(mm, address, pmd, _pmd);
@@ -1856,6 +1856,7 @@ static void collapse_huge_page(struct mm_struct *mm,
anon_vma_unlock(vma->anon_vma);
__collapse_huge_page_copy(pte, new_page, vma, address, ptl);
+ pte_unmap(pte);
__SetPageUptodate(new_page);
pgtable = pmd_pgtable(_pmd);
VM_BUG_ON(page_count(pgtable) != 1);