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>
diff --git a/mm/memory.c b/mm/memory.c
index c50a195..840ce9d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1288,7 +1288,7 @@
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;