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authorDavid Rientjes <rientjes@google.com>2016-12-12 16:42:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-12 18:55:07 -0800
commitfd60775aea802beef444881ddfa111a4b73b1bbc (patch)
treedb96e02edd1a97205c8b420d7309d2956e6f0e3a /mm/mprotect.c
parent3f5000693f80e014fa577b67b93a0de945a4338d (diff)
mm, thp: avoid unlikely branches for split_huge_pmd
While doing MADV_DONTNEED on a large area of thp memory, I noticed we encountered many unlikely() branches in profiles for each backing hugepage. This is because zap_pmd_range() would call split_huge_pmd(), which rechecked the conditions that were already validated, but as part of an unlikely() branch. Avoid the unlikely() branch when in a context where pmd is known to be good for __split_huge_pmd() directly. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1610181600300.84525@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mprotect.c')
-rw-r--r--mm/mprotect.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 05a02b72c98d..c5ba2aae0f54 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -176,7 +176,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE) {
- split_huge_pmd(vma, pmd, addr);
+ __split_huge_pmd(vma, pmd, addr, false, NULL);
if (pmd_trans_unstable(pmd))
continue;
} else {