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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-10-09 11:51:45 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-12-04 10:52:56 -0800
commit08df477434754629303c9e2bfa8d67ecb44f9c20 (patch)
tree98e412d75e903798d8332f9760a2f660c6c76a1c /mm/ksm.c
parent516df050615e4b0fd2dd0448cb5a807208a3837a (diff)
mm/ksm: Remove now-redundant smp_read_barrier_depends()
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 <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: <linux-mm@kvack.org>
Diffstat (limited to 'mm/ksm.c')
-rw-r--r--mm/ksm.c9
1 files changed, 1 insertions, 8 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index be8f4576f842..c406f75957ad 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;