3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mel Gorman <mgor...@suse.de>
commit 0cee34fd72c582b4f8ad8ce00645b75fb4168199 upstream.
Stable note: Not tracked on Bugzilla. THP and compaction was found to
aggressively reclaim pages and stall systems under different
situations that was addressed piecemeal over time.
If compaction can proceed for a given zone, shrink_zones() does not
reclaim any more pages from it. After commit [e0c2327: vmscan: abort
reclaim/compaction if compaction can proceed], do_try_to_free_pages()
tries to finish as soon as possible once one zone can compact.
This was intended to prevent slabs being shrunk unnecessarily but there
are side-effects. One is that a small zone that is ready for compaction
will abort reclaim even if the chances of successfully allocating a THP
from that zone is small. It also means that reclaim can return too early
even though sc->nr_to_reclaim pages were not reclaimed.
This partially reverts the commit until it is proven that slabs are really
being shrunk unnecessarily but preserves the check to return 1 to avoid
OOM if reclaim was aborted prematurely.
[aarca...@redhat.com: This patch replaces a revert from Andrea]
Signed-off-by: Mel Gorman <mgor...@suse.de>
Reviewed-by: Rik van Riel <r...@redhat.com>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Cc: Minchan Kim <minchan....@gmail.com>
Cc: Dave Jones <da...@redhat.com>
Cc: Jan Kara <j...@suse.cz>
Cc: Andy Isaacson <a...@hexapodia.org>
Cc: Nai Xia <nai....@gmail.com>
Cc: Johannes Weiner <jwei...@redhat.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
mm/vmscan.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2173,7 +2173,8 @@ static inline bool compaction_ready(stru
*
* This function returns true if a zone is being reclaimed for a costly
* high-order allocation and compaction is ready to begin. This indicates to
- * the caller that it should retry the allocation or fail.
+ * the caller that it should consider retrying the allocation instead of
+ * further reclaim.
*/
static bool shrink_zones(int priority, struct zonelist *zonelist,
struct scan_control *sc)
@@ -2182,7 +2183,7 @@ static bool shrink_zones(int priority, s
struct zone *zone;
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
- bool should_abort_reclaim = false;
+ bool aborted_reclaim = false;
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) {
@@ -2208,7 +2209,7 @@ static bool shrink_zones(int priority, s
* allocations.
*/
if (compaction_ready(zone, sc)) {
- should_abort_reclaim = true;
+ aborted_reclaim = true;
continue;
}
}
@@ -2230,7 +2231,7 @@ static bool shrink_zones(int priority, s
shrink_zone(priority, zone, sc);
}
- return should_abort_reclaim;
+ return aborted_reclaim;
}
static bool zone_reclaimable(struct zone *zone)
@@ -2284,7 +2285,7 @@ static unsigned long do_try_to_free_page
struct zoneref *z;
struct zone *zone;
unsigned long writeback_threshold;
- bool should_abort_reclaim;
+ bool aborted_reclaim;
get_mems_allowed();
delayacct_freepages_start();
@@ -2296,9 +2297,7 @@ static unsigned long do_try_to_free_page
sc->nr_scanned = 0;
if (!priority)
disable_swap_token(sc->mem_cgroup);
- should_abort_reclaim = shrink_zones(priority, zonelist, sc);
- if (should_abort_reclaim)
- break;
+ aborted_reclaim = shrink_zones(priority, zonelist, sc);
/*
* Don't shrink slabs when reclaiming memory from
@@ -2365,8 +2364,8 @@ out:
if (oom_killer_disabled)
return 0;
- /* Aborting reclaim to try compaction? don't OOM, then */
- if (should_abort_reclaim)
+ /* Aborted reclaim to try compaction? don't OOM, then */
+ if (aborted_reclaim)
return 1;
/* top priority shrink_zones still had more to do? don't OOM, then */
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
