mm: make unreserve highatomic functions reliable
Currently, unreserve_highatomic_pageblock bails out if it found
highatomic pageblock regardless of really moving free pages from the one
so that it could mitigate unreserve logic's goal which saves OOM of a
process.
This patch makes unreserve functions bail out only if it moves some
pages out of !highatomic free list to avoid such false positive.
Another potential problem is that by race between page freeing and
reserve highatomic function, pages could be in highatomic free list even
though the pageblock is !high atomic migratetype. In that case,
unreserve_highatomic_pageblock can be void if count of highatomic
reserve is less than pageblock_nr_pages. We could solve it simply via
draining all of reserved pages before the OOM. It would have a
safeguard role to exhuast reserved pages before converging to OOM.
Change-Id: Ia995e39944c38f803901bf57f97db8558501f8d6
Link: http://lkml.kernel.org/r/1476259429-18279-5-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sangseok Lee <sangseok.lee@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 29fac03bef729ef6f9fba5be56f8554093813c39
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 11a2d6c..f61724f4f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2058,8 +2058,12 @@
* potentially hurts the reliability of high-order allocations when under
* intense memory pressure but failed atomic allocations should be easier
* to recover from than an OOM.
+ *
+ * If @force is true, try to unreserve a pageblock even though highatomic
+ * pageblock is exhausted.
*/
-static bool unreserve_highatomic_pageblock(const struct alloc_context *ac)
+static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
+ bool force)
{
struct zonelist *zonelist = ac->zonelist;
unsigned long flags;
@@ -2071,8 +2075,12 @@
for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx,
ac->nodemask) {
- /* Preserve at least one pageblock */
- if (zone->nr_reserved_highatomic <= pageblock_nr_pages)
+ /*
+ * Preserve at least one pageblock unless memory pressure
+ * is really high.
+ */
+ if (!force && zone->nr_reserved_highatomic <=
+ pageblock_nr_pages)
continue;
spin_lock_irqsave(&zone->lock, flags);
@@ -2117,8 +2125,10 @@
*/
set_pageblock_migratetype(page, ac->migratetype);
ret = move_freepages_block(zone, page, ac->migratetype);
- spin_unlock_irqrestore(&zone->lock, flags);
- return ret;
+ if (ret) {
+ spin_unlock_irqrestore(&zone->lock, flags);
+ return ret;
+ }
}
spin_unlock_irqrestore(&zone->lock, flags);
}
@@ -3330,7 +3340,7 @@
* Shrink them them and try again
*/
if (!page && !drained) {
- unreserve_highatomic_pageblock(ac);
+ unreserve_highatomic_pageblock(ac, false);
drain_all_pages(NULL);
drained = true;
goto retry;
@@ -3449,7 +3459,7 @@
*/
if (*no_progress_loops > MAX_RECLAIM_RETRIES) {
/* Before OOM, exhaust highatomic_reserve */
- return unreserve_highatomic_pageblock(ac);
+ return unreserve_highatomic_pageblock(ac, true);
}
/*