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thp: transparent hugepage core fixlet 

If you configure THP in addition to HUGETLB_PAGE on x86_32 without PAE,
the p?d-folding works out that munlock_vma_pages_range() can crash to
follow_page()'s pud_huge() BUG_ON(flags & FOLL_GET): it needs the same
VM_HUGETLB check already there on the pmd_huge() line.  Conveniently,
openSUSE provides a "blogd" which tests this out at startup!

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2011-01-13 15:46:52 -08:00 committed by Linus Torvalds
parent 71e3aac072
commit 8a07651ee8
1 changed files with 1 additions and 1 deletions
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2
mm/memory.c
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@ -1288,7 +1288,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
pud = pud_offset(pgd, address);
if (pud_none(*pud))
goto no_page_table;
if (pud_huge(*pud)) {
if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
BUG_ON(flags & FOLL_GET);
page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
goto out;