The patch titled
Subject: ksm: replace smp_read_barrier_depends() with lockless_dereference()
has been added to the -mm tree. Its filename is
ksm-replace-smp_read_barrier_depends-with-lockless_dereference.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ksm-replace-smp_read_barrier_depends-with-lockless_dereference.patch
echo and later at
echo http://ozlabs.org/~akpm/mmotm/broken-out/ksm-replace-smp_read_barrier_depends-with-lockless_dereference.patch
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------------------------------------------------------
From: Pranith Kumar <bobby.prani@xxxxxxxxx>
Subject: ksm: replace smp_read_barrier_depends() with lockless_dereference()
Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the
change.
Signed-off-by: Pranith Kumar <bobby.prani@xxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff -puN mm/ksm.c~ksm-replace-smp_read_barrier_depends-with-lockless_dereference mm/ksm.c
--- a/mm/ksm.c~ksm-replace-smp_read_barrier_depends-with-lockless_dereference
+++ a/mm/ksm.c
@@ -542,15 +542,14 @@ static struct page *get_ksm_page(struct
expected_mapping = (void *)stable_node +
(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
again:
- kpfn = ACCESS_ONCE(stable_node->kpfn);
- page = pfn_to_page(kpfn);
-
/*
* page is computed from kpfn, so on most architectures reading
* page->mapping is naturally ordered after reading node->kpfn,
* but on Alpha we need to be more careful.
*/
- smp_read_barrier_depends();
+ kpfn = lockless_dereference(stable_node->kpfn);
+ page = pfn_to_page(kpfn);
+
if (ACCESS_ONCE(page->mapping) != expected_mapping)
goto stale;
_
Patches currently in -mm which might be from bobby.prani@xxxxxxxxx are
ksm-replace-smp_read_barrier_depends-with-lockless_dereference.patch
linux-next.patch
slab-replace-smp_read_barrier_depends-with-lockless_dereference.patch
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