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authorMel Gorman <mgorman@techsingularity.net>2016-07-28 15:47:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-28 16:07:41 -0700
commitd7f05528eedb047efe2288cff777676b028747b6 (patch)
treedab403a296f8a7ab6bdf2a6a28cad43fdaaddd5f /mm/vmscan.c
parentf8d1a31163fcb3bf93f6c78770c3c1915f065bf9 (diff)
downloadlinux-d7f05528eedb047efe2288cff777676b028747b6.tar.bz2
mm, vmscan: account for skipped pages as a partial scan
Page reclaim determines whether a pgdat is unreclaimable by examining how many pages have been scanned since a page was freed and comparing that to the LRU sizes. Skipped pages are not reclaim candidates but contribute to scanned. This can prematurely mark a pgdat as unreclaimable and trigger an OOM kill. This patch accounts for skipped pages as a partial scan so that an unreclaimable pgdat will still be marked as such but by scaling the cost of a skip, it'll avoid the pgdat being marked prematurely. Link: http://lkml.kernel.org/r/1469110261-7365-6-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f7b958b9aea9..0294ab34f475 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1424,7 +1424,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
LIST_HEAD(pages_skipped);
for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
- !list_empty(src); scan++) {
+ !list_empty(src);) {
struct page *page;
page = lru_to_page(src);
@@ -1438,6 +1438,12 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
continue;
}
+ /*
+ * Account for scanned and skipped separetly to avoid the pgdat
+ * being prematurely marked unreclaimable by pgdat_reclaimable.
+ */
+ scan++;
+
switch (__isolate_lru_page(page, mode)) {
case 0:
nr_pages = hpage_nr_pages(page);
@@ -1465,14 +1471,24 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
*/
if (!list_empty(&pages_skipped)) {
int zid;
+ unsigned long total_skipped = 0;
- list_splice(&pages_skipped, src);
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
if (!nr_skipped[zid])
continue;
__count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
+ total_skipped += nr_skipped[zid];
}
+
+ /*
+ * Account skipped pages as a partial scan as the pgdat may be
+ * close to unreclaimable. If the LRU list is empty, account
+ * skipped pages as a full scan.
+ */
+ scan += list_empty(src) ? total_skipped : total_skipped >> 2;
+
+ list_splice(&pages_skipped, src);
}
*nr_scanned = scan;
trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, scan,