Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1567933

[PATCH 1/2 v2] mm: vmscan: do not pass reclaimed slab to vmpressure

Show all headers | View raw

It is noticed that during a global reclaim the memory
reclaimed via shrinking the slabs can sometimes result
in reclaimed pages being greater than the scanned pages
in shrink_node. When this is passed to vmpressure, the
unsigned arithmetic results in the pressure value to be
huge, thus resulting in a critical event being sent to
root cgroup. While this can be fixed by underflow checks
in vmpressure, adding reclaimed slab without a corresponding
increment of nr_scanned results in incorrect vmpressure
reporting. So do not consider reclaimed slab pages in
vmpressure calculation.

Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
---
 mm/vmscan.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 947ab6f..37c4486 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2594,16 +2594,16 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 				    sc->nr_scanned - nr_scanned,
 				    node_lru_pages);
 
-		if (reclaim_state) {
-			sc->nr_reclaimed += reclaim_state->reclaimed_slab;
-			reclaim_state->reclaimed_slab = 0;
-		}
-
 		/* Record the subtree's reclaim efficiency */
 		vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
 			   sc->nr_scanned - nr_scanned,
 			   sc->nr_reclaimed - nr_reclaimed);
 
+		if (reclaim_state) {
+			sc->nr_reclaimed += reclaim_state->reclaimed_slab;
+			reclaim_state->reclaimed_slab = 0;
+		}
+
 		if (sc->nr_reclaimed - nr_reclaimed)
 			reclaimable = true;
 
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH 1/2 v2] mm: vmscan: do not pass reclaimed slab to vmpressure Vinayak Menon <vinmenon@codeaurora.org> - 2017-01-27 09:20 +0100
  [PATCH 2/2] mm: vmpressure: fix sending wrong events on underflow Vinayak Menon <vinmenon@codeaurora.org> - 2017-01-27 09:20 +0100

csiph-web