The patch "mm: vmscan: Block kswapd if it is encountering pages
under writeback" stalls in congestion_wait it encounters a page under
writeback that is marked for immediate reclaim. Initially this was a
wait_on_page_writeback() but after the switch to congestion_wait(),
there is no guarantee the page has completed writeback and it can
be placed on a list for freeing.
This is a fix for
mm-vmscan-block-kswapd-if-it-is-encountering-pages-under-writeback.patch
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
mm/vmscan.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b1b38ad..4a43c28 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -766,8 +766,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
if (current_is_kswapd() &&
PageReclaim(page) &&
zone_is_reclaim_writeback(zone)) {
+ unlock_page(page);
congestion_wait(BLK_RW_ASYNC, HZ/10);
zone_clear_flag(zone, ZONE_WRITEBACK);
+ goto keep;
/* Case 2 above */
} else if (global_reclaim(sc) ||
--
1.8.1.4
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