Re: [PATCH 1/4] mm: thp: Return the correct value for change_huge_pmd
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: 2015-03-07 20:13:30
Also in:
linux-mm, linux-xfs, lkml
Looks obviously correct. The old code was just very wrong.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus
On Sat, Mar 7, 2015 at 7:20 AM, Mel Gorman [off-list ref] wrote:quoted hunk ↗ jump to hunk
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