* [PATCH] thp, dax: do not try to withdraw pgtable from non-anon VMA
@ 2016-02-11 2:40 Kirill A. Shutemov
0 siblings, 0 replies; only message in thread
From: Kirill A. Shutemov @ 2016-02-11 2:40 UTC (permalink / raw)
To: Andrew Morton, Dan Williams, Matthew Wilcox
Cc: Andrea Arcangeli, Ross Zwisler, linux-mm, linux-kernel,
Kirill A. Shutemov
DAX doesn't deposit pgtables when it maps huge pages: nothing to
withdraw. It can lead to crash.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/huge_memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5404f7534366..ca7f21516c3a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1706,7 +1706,8 @@ bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
VM_BUG_ON(!pmd_none(*new_pmd));
- if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
+ if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
+ vma_is_anonymous(vma)) {
pgtable_t pgtable;
pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
--
2.7.0
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