The patch titled
mm: vmscan: correctly check if reclaimer should schedule during shrink_slab
has been added to the -mm tree. Its filename is
mm-vmscan-correctly-check-if-reclaimer-should-schedule-during-shrink_slab.patch
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Subject: mm: vmscan: correctly check if reclaimer should schedule during shrink_slab
From: Minchan Kim <minchan.kim@xxxxxxxxx>
It has been reported on some laptops that kswapd is consuming large
amounts of CPU and not being scheduled when SLUB is enabled during large
amounts of file copying. It is expected that this is due to kswapd
missing every cond_resched() point because;
shrink_page_list() calls cond_resched() if inactive pages were isolated
which in turn may not happen if all_unreclaimable is set in
shrink_zones(). If for whatver reason, all_unreclaimable is
set on all zones, we can miss calling cond_resched().
balance_pgdat() only calls cond_resched if the zones are not
balanced. For a high-order allocation that is balanced, it
checks order-0 again. During that window, order-0 might have
become unbalanced so it loops again for order-0 and returns
that it was reclaiming for order-0 to kswapd(). It can then
find that a caller has rewoken kswapd for a high-order and
re-enters balance_pgdat() without ever calling cond_resched().
shrink_slab only calls cond_resched() if we are reclaiming slab
pages. If there are a large number of direct reclaimers, the
shrinker_rwsem can be contended and prevent kswapd calling
cond_resched().
This patch modifies the shrink_slab() case. If the semaphore is
contended, the caller will still check cond_resched(). After each
successful call into a shrinker, the check for cond_resched() remains in
case one shrinker is particularly slow.
[mgorman@xxxxxxx: Preserve call to cond_resched after each call into shrinker]
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: Colin King <colin.king@xxxxxxxxxxxxx>
Cc: Raghavendra D Prabhu <raghu.prabhu13@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Chris Mason <chris.mason@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: <stable@xxxxxxxxxx> [2.6.38+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff -puN mm/vmscan.c~mm-vmscan-correctly-check-if-reclaimer-should-schedule-during-shrink_slab mm/vmscan.c
--- a/mm/vmscan.c~mm-vmscan-correctly-check-if-reclaimer-should-schedule-during-shrink_slab
+++ a/mm/vmscan.c
@@ -231,8 +231,11 @@ unsigned long shrink_slab(unsigned long
if (scanned == 0)
scanned = SWAP_CLUSTER_MAX;
- if (!down_read_trylock(&shrinker_rwsem))
- return 1; /* Assume we'll be able to shrink next time */
+ if (!down_read_trylock(&shrinker_rwsem)) {
+ /* Assume we'll be able to shrink next time */
+ ret = 1;
+ goto out;
+ }
list_for_each_entry(shrinker, &shrinker_list, list) {
unsigned long long delta;
@@ -283,6 +286,8 @@ unsigned long shrink_slab(unsigned long
shrinker->nr += total_scan;
}
up_read(&shrinker_rwsem);
+out:
+ cond_resched();
return ret;
}
_
Patches currently in -mm which might be from minchan.kim@xxxxxxxxx are
mm-vmscan-correct-use-of-pgdat_balanced-in-sleeping_prematurely.patch
mm-vmscan-correctly-check-if-reclaimer-should-schedule-during-shrink_slab.patch
linux-next.patch
mm-introduce-wait_on_page_locked_killable.patch
x86mm-make-pagefault-killable.patch
mm-mem-hotplug-fix-section-mismatch-setup_per_zone_inactive_ratio-should-be-__meminit.patch
mm-mem-hotplug-recalculate-lowmem_reserve-when-memory-hotplug-occur.patch
oom-replace-pf_oom_origin-with-toggling-oom_score_adj.patch
oom-replace-pf_oom_origin-with-toggling-oom_score_adj-update.patch
mm-thp-optimize-memcg-charge-in-khugepaged.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix-fix.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix-fix-fix.patch
writeback-elevate-queue_io-into-wb_writeback.patch
mm-check-if-any-page-in-a-pageblock-is-reserved-before-marking-it-migrate_reserve-fix-2.patch
readahead-readahead-page-allocations-are-ok-to-fail.patch
vmscan-change-shrink_slab-interfaces-by-passing-shrink_control.patch
vmscan-change-shrink_slab-interfaces-by-passing-shrink_control-fix.patch
vmscan-change-shrink_slab-interfaces-by-passing-shrink_control-fix-2.patch
vmscan-change-shrinker-api-by-passing-shrink_control-struct.patch
vmscan-change-shrinker-api-by-passing-shrink_control-struct-fix.patch
vmscan-change-shrinker-api-by-passing-shrink_control-struct-fix-2.patch
vmscan-change-shrinker-api-by-passing-shrink_control-struct-fix-3.patch
mm-filter-unevictable-page-out-in-deactivate_page.patch
mm-filter-unevictable-page-out-in-deactivate_page-fix.patch
mm-filter-unevictable-page-out-in-deactivate_page-fix-fix.patch
mm-page_allocc-prevent-unending-loop-in-__alloc_pages_slowpath.patch
mm-batch-activate_page-to-reduce-lock-contention.patch
mm-move-enum-vm_event_item-into-a-standalone-header-file.patch
memcg-count-the-soft_limit-reclaim-in-global-background-reclaim.patch
memcg-add-the-soft_limit-reclaim-in-global-direct-reclaim.patch
memcg-rename-mem_cgroup_zone_nr_pages-to-mem_cgroup_zone_nr_lru_pages.patch
memcg-add-memorynumastat-api-for-numa-statistics.patch
memcg-add-memorynumastat-api-for-numa-statistics-v5.patch
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