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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 <weijie.yang@samsung.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Weijie Yang 2014-04-07 15:36:59 -07:00 committed by Linus Torvalds
parent a5338093bf
commit 619d0d76c1
1 changed files with 8 additions and 0 deletions
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8
mm/vmscan.c
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@ -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;
}