We promote sc->gfp_mask to __GFP_HIGHMEM to forcibly scan highmem if
there are too many buffer_heads pinning highmem. see: cc715d99e5
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@xxxxxxxxxxx>
---
mm/vmscan.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
mode change 100644 => 100755 mm/vmscan.c
diff --git a/mm/vmscan.c b/mm/vmscan.c
old mode 100644
new mode 100755
index a9c74b4..35879f0
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2298,14 +2298,17 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
bool aborted_reclaim = false;
+ bool promoted_mask = false;
/*
* If the number of buffer_heads in the machine exceeds the maximum
* allowed level, force direct reclaim to scan the highmem zone as
* highmem pages could be pinning lowmem pages storing buffer_heads
*/
- if (buffer_heads_over_limit)
+ if (buffer_heads_over_limit) {
+ promoted_mask = !(sc->gfp_mask & __GFP_HIGHMEM);
sc->gfp_mask |= __GFP_HIGHMEM;
+ }
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) {
@@ -2354,6 +2357,9 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
shrink_zone(zone, sc);
}
+ if (promoted_mask)
+ sc->gfp_mask &= ~__GFP_HIGHMEM;
+
return aborted_reclaim;
}
--
1.7.10.4
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