[PATCH 1/2] mm: thp: Return the correct value for change_huge_pmd

Mel Gorman
2015-03-05T23:55:04Z

The wrong value is being returned by change_huge_pmd since commit
10c1045f28e8 ("mm: numa: avoid unnecessary TLB flushes when setting
NUMA hinting entries") which allows a fallthrough that tries to adjust
non-existent PTEs. This patch corrects it.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/huge_memory.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index fc00c8cb5a82..194c0f019774 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1482,6 +1482,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,

if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
pmd_t entry;
+ ret = 1;

/*
* Avoid trapping faults against the zero page. The read-only
@@ -1490,11 +1491,10 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
*/
if (prot_numa && is_huge_zero_pmd(*pmd)) {
spin_unlock(ptl);
- return 0;
+ return ret;
}

if (!prot_numa || !pmd_protnone(*pmd)) {
- ret = 1;
entry = pmdp_get_and_clear_notify(mm, addr, pmd);
entry = pmd_modify(entry, newprot);
ret = HPAGE_PMD_NR;
--
2.1.2