This is a note to let you know that I've just added the patch titled
mm/compaction: stop isolation if too many pages are isolated and we have pages to migrate
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-compaction-stop-isolation-if-too-many-pages-are-isolated-and-we-have-pages-to-migrate.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d20bdd571ee5c9966191568527ecdb1bd4b52368 Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@xxxxxxxxxx>
Date: Fri, 13 Nov 2020 22:51:43 -0800
Subject: mm/compaction: stop isolation if too many pages are isolated and we have pages to migrate
MIME-Version: 1.0
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From: Zi Yan <ziy@xxxxxxxxxx>
commit d20bdd571ee5c9966191568527ecdb1bd4b52368 upstream.
In isolate_migratepages_block, if we have too many isolated pages and
nr_migratepages is not zero, we should try to migrate what we have
without wasting time on isolating.
In theory it's possible that multiple parallel compactions will cause
too_many_isolated() to become true even if each has isolated less than
COMPACT_CLUSTER_MAX, and loop forever in the while loop. Bailing
immediately prevents that.
[vbabka@xxxxxxx: changelog addition]
Fixes: 1da2f328fa64 (“mm,thp,compaction,cma: allow THP migration for CMA allocations”)
Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20201030183809.3616803-2-zi.yan@xxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -818,6 +818,10 @@ isolate_migratepages_block(struct compac
* delay for some time until fewer pages are isolated
*/
while (unlikely(too_many_isolated(pgdat))) {
+ /* stop isolation if there are still pages not migrated */
+ if (cc->nr_migratepages)
+ return 0;
+
/* async migration should just abort */
if (cc->mode == MIGRATE_ASYNC)
return 0;
Patches currently in stable-queue which might be from ziy@xxxxxxxxxx are
queue-5.9/mm-compaction-count-pages-and-stop-correctly-during-page-isolation.patch
queue-5.9/mm-compaction-stop-isolation-if-too-many-pages-are-isolated-and-we-have-pages-to-migrate.patch
