Because READ_ONCE() now implies smp_read_barrier_depends(), the
smp_read_barrier_depends() in get_ksm_page() is now redundant.
This commit removes it and updates the comments.
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Cc: Minchan Kim <minc...@kernel.org>
Cc: Michal Hocko <mho...@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shute...@linux.intel.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
Cc: Claudio Imbrenda <imbre...@linux.vnet.ibm.com>
Cc: <linux...@kvack.org>
---
mm/ksm.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/mm/ksm.c b/mm/ksm.c
index 6cb60f46cce5..7d70f923bc45 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -675,15 +675,8 @@ static struct page *get_ksm_page(struct stable_node
*stable_node, bool lock_it)
expected_mapping = (void *)((unsigned long)stable_node |
PAGE_MAPPING_KSM);
again:
- kpfn = READ_ONCE(stable_node->kpfn);
+ kpfn = READ_ONCE(stable_node->kpfn); /* Address dependency. */
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();
if (READ_ONCE(page->mapping) != expected_mapping)
goto stale;
--
2.5.2
