2014-02-14 06:42:33

by Weijie Yang

Subject: [PATCH V2 1/2] 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

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 <[email protected]>
---
Changes since v1:
- use orig_mask to record the caller's orininal mask and restore
it after finishing scan, according to Riel's suggestion.

V1: https://lkml.org/lkml/2014/2/12/764

mm/vmscan.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a9c74b4..da0a87c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2298,6 +2298,7 @@ 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;
+ gfp_t orig_mask = sc->gfp_mask;

/*
* If the number of buffer_heads in the machine exceeds the maximum
@@ -2354,6 +2355,12 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
shrink_zone(zone, sc);
}

+ /*
+ * restore to original mask to avoid the impact on its caller
+ * if we promote it to __GFP_HIGHMEM.
+ */
+ sc->gfp_mask = orig_mask;
+
return aborted_reclaim;
}

--
1.7.10.4

2014-02-14 11:04:25

by Mel Gorman

Subject: Re: [PATCH V2 1/2] mm/vmscan: restore sc->gfp_mask after promoting it to __GFP_HIGHMEM

On Fri, Feb 14, 2014 at 02:41:33PM +0800, Weijie Yang wrote:
> 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 <[email protected]>

Acked-by: Mel Gorman <[email protected]>

--
Mel Gorman
SUSE Labs

2014-02-14 14:16:02

by Rik van Riel

Subject: Re: [PATCH V2 1/2] mm/vmscan: restore sc->gfp_mask after promoting it to __GFP_HIGHMEM

On 02/14/2014 01:41 AM, Weijie Yang wrote:
> 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 <[email protected]>

Acked-by: Rik van Riel <[email protected]>

--
All rights reversed