This is a note to let you know that I've just added the patch titled
mm/compaction: change the timing to check to drop the spinlock
to the 3.14-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-change-the-timing-to-check-to-drop-the-spinlock.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From be1aa03b973c7dcdc576f3503f7a60429825c35d Mon Sep 17 00:00:00 2001
From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Date: Mon, 7 Apr 2014 15:37:05 -0700
Subject: mm/compaction: change the timing to check to drop the spinlock
From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
commit be1aa03b973c7dcdc576f3503f7a60429825c35d upstream.
It is odd to drop the spinlock when we scan (SWAP_CLUSTER_MAX - 1) th
pfn page. This may results in below situation while isolating
migratepage.
1. try isolate 0x0 ~ 0x200 pfn pages.
2. When low_pfn is 0x1ff, ((low_pfn+1) % SWAP_CLUSTER_MAX) == 0, so drop
the spinlock.
3. Then, to complete isolating, retry to aquire the lock.
I think that it is better to use SWAP_CLUSTER_MAX th pfn for checking the
criteria about dropping the lock. This has no harm 0x0 pfn, because, at
this time, locked variable would be false.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -487,7 +487,7 @@ isolate_migratepages_range(struct zone *
cond_resched();
for (; low_pfn < end_pfn; low_pfn++) {
/* give a chance to irqs before checking need_resched() */
- if (locked && !((low_pfn+1) % SWAP_CLUSTER_MAX)) {
+ if (locked && !(low_pfn % SWAP_CLUSTER_MAX)) {
if (should_release_lock(&zone->lru_lock)) {
spin_unlock_irqrestore(&zone->lru_lock, flags);
locked = false;
Patches currently in stable-queue which might be from iamjoonsoo.kim@xxxxxxx are
queue-3.14/mm-compaction-avoid-isolating-pinned-pages.patch
queue-3.14/mm-compaction-do-not-call-suitable_migration_target-on-every-page.patch
queue-3.14/mm-compaction-determine-isolation-mode-only-once.patch
queue-3.14/mm-compaction-check-pageblock-suitability-once-per-pageblock.patch
queue-3.14/mm-compaction-clean-up-code-on-success-of-ballon-isolation.patch
queue-3.14/mm-compaction-disallow-high-order-page-for-migration-target.patch
queue-3.14/mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch
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