The patch titled
Subject: ksm: treat unstable nid like in stable tree
has been removed from the -mm tree. Its filename was
ksm-treat-unstable-nid-like-in-stable-tree.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: ksm: treat unstable nid like in stable tree
An inconsistency emerged in reviewing the NUMA node changes to KSM: when
meeting a page from the wrong NUMA node in a stable tree, we say that it's
okay for comparisons, but not as a leaf for merging; whereas when meeting
a page from the wrong NUMA node in an unstable tree, we bail out
immediately.
Now, it might be that a wrong NUMA node in an unstable tree is more likely
to correlate with instablility (different content, with rbnode now
misplaced) than page migration; but even so, we are accustomed to
instablility in the unstable tree.
Without strong evidence for which strategy is generally better, I'd rather
be consistent with what's done in the stable tree: accept a page from the
wrong NUMA node for comparison, but not as a leaf for merging.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Petr Holasek <pholasek@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Izik Eidus <izik.eidus@xxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff -puN mm/ksm.c~ksm-treat-unstable-nid-like-in-stable-tree mm/ksm.c
--- a/mm/ksm.c~ksm-treat-unstable-nid-like-in-stable-tree
+++ a/mm/ksm.c
@@ -1342,16 +1342,6 @@ struct rmap_item *unstable_tree_search_i
return NULL;
}
- /*
- * If tree_page has been migrated to another NUMA node, it
- * will be flushed out and put into the right unstable tree
- * next time: only merge with it if merge_across_nodes.
- */
- if (!ksm_merge_across_nodes && page_to_nid(tree_page) != nid) {
- put_page(tree_page);
- return NULL;
- }
-
ret = memcmp_pages(page, tree_page);
parent = *new;
@@ -1361,6 +1351,15 @@ struct rmap_item *unstable_tree_search_i
} else if (ret > 0) {
put_page(tree_page);
new = &parent->rb_right;
+ } else if (!ksm_merge_across_nodes &&
+ page_to_nid(tree_page) != nid) {
+ /*
+ * If tree_page has been migrated to another NUMA node,
+ * it will be flushed out and put in the right unstable
+ * tree next time: only merge with it when across_nodes.
+ */
+ put_page(tree_page);
+ return NULL;
} else {
*tree_pagep = tree_page;
return tree_rmap_item;
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
origin.patch
revert-x86-mm-make-spurious_fault-check-explicitly-check-the-present-bit.patch
pageattr-prevent-pse-and-gloabl-leftovers-to-confuse-pmd-pte_present-and-pmd_huge.patch
mm-accelerate-munlock-treatment-of-thp-pages.patch
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