The patch titled
Subject: ksm: don't fail stable tree lookups if walking over stale stable_nodes
has been added to the -mm tree. Its filename is
ksm-dont-fail-stable-tree-lookups-if-walking-over-stale-stable_nodes-v2.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ksm-dont-fail-stable-tree-lookups-if-walking-over-stale-stable_nodes-v2.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ksm-dont-fail-stable-tree-lookups-if-walking-over-stale-stable_nodes-v2.patch
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------------------------------------------------------
From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject: ksm: don't fail stable tree lookups if walking over stale stable_nodes
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
diff -puN mm/ksm.c~ksm-dont-fail-stable-tree-lookups-if-walking-over-stale-stable_nodes-v2 mm/ksm.c
--- a/mm/ksm.c~ksm-dont-fail-stable-tree-lookups-if-walking-over-stale-stable_nodes-v2
+++ a/mm/ksm.c
@@ -1177,7 +1177,7 @@ again:
cond_resched();
stable_node = rb_entry(*new, struct stable_node, node);
tree_page = get_ksm_page(stable_node, false);
- if (!tree_page)
+ if (!tree_page) {
/*
* If we walked over a stale stable_node,
* get_ksm_page() will call rb_erase() and it
@@ -1185,11 +1185,10 @@ again:
* restart the search from scratch. Returning
* NULL would be safe too, but we'd generate
* false negative insertions just because some
- * stable_node was stale which would waste CPU
- * by doing the preparation work twice at the
- * next KSM pass.
+ * stable_node was stale.
*/
goto again;
+ }
ret = memcmp_pages(page, tree_page);
put_page(tree_page);
@@ -1282,7 +1281,7 @@ again:
cond_resched();
stable_node = rb_entry(*new, struct stable_node, node);
tree_page = get_ksm_page(stable_node, false);
- if (!tree_page)
+ if (!tree_page) {
/*
* If we walked over a stale stable_node,
* get_ksm_page() will call rb_erase() and it
@@ -1290,11 +1289,10 @@ again:
* restart the search from scratch. Returning
* NULL would be safe too, but we'd generate
* false negative insertions just because some
- * stable_node was stale which would waste CPU
- * by doing the preparation work twice at the
- * next KSM pass.
+ * stable_node was stale.
*/
goto again;
+ }
ret = memcmp_pages(kpage, tree_page);
put_page(tree_page);
_
Patches currently in -mm which might be from aarcange@xxxxxxxxxx are
ksm-add-cond_resched-to-the-rmap_walks.patch
ksm-dont-fail-stable-tree-lookups-if-walking-over-stale-stable_nodes.patch
ksm-dont-fail-stable-tree-lookups-if-walking-over-stale-stable_nodes-v2.patch
ksm-use-the-helper-method-to-do-the-hlist_empty-check.patch
ksm-use-find_mergeable_vma-in-try_to_merge_with_ksm_page.patch
ksm-unstable_tree_search_insert-error-checking-cleanup.patch
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