From 619d0d76c1ee943f171c7d4fc021ec7602388579 Mon Sep 17 00:00:00 2001 From: Weijie Yang Date: Mon, 7 Apr 2014 15:36:59 -0700 Subject: [PATCH] mm/vmscan: restore sc->gfp_mask after promoting it to __GFP_HIGHMEM We promote sc->gfp_mask to __GFP_HIGHMEM to forcibly scan highmem if there are too many buffer_heads pinning highmem. See cc715d99e5 ("mm: vmscan: forcibly scan highmem if there are too many buffer_heads pinning highmem"). This patch restores sc->gfp_mask to its caller original value after finishing the scan job, to avoid the impact on other invocations from its upper caller, such as vmpressure_prio(), shrink_slab(). Signed-off-by: Weijie Yang Acked-by: Mel Gorman Acked-by: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index 1f56a80a7c41..1c51e4f52fd9 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2314,6 +2314,7 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) unsigned long lru_pages = 0; bool aborted_reclaim = false; struct reclaim_state *reclaim_state = current->reclaim_state; + gfp_t orig_mask; struct shrink_control shrink = { .gfp_mask = sc->gfp_mask, }; @@ -2323,6 +2324,7 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) * allowed level, force direct reclaim to scan the highmem zone as * highmem pages could be pinning lowmem pages storing buffer_heads */ + orig_mask = sc->gfp_mask; if (buffer_heads_over_limit) sc->gfp_mask |= __GFP_HIGHMEM; @@ -2393,6 +2395,12 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc) } } + /* + * Restore to original mask to avoid the impact on the caller if we + * promoted it to __GFP_HIGHMEM. + */ + sc->gfp_mask = orig_mask; + return aborted_reclaim; }