The patch titled
vmscan: fix use of delta in zone_pagecache_reclaimable()
has been added to the -mm tree. Its filename is
vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-reclaim-vmscan-fix-use-of-delta-in-zone_pagecache_reclaimable.patch
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Subject: vmscan: fix use of delta in zone_pagecache_reclaimable()
From: Mel Gorman <mel@xxxxxxxxx>
zone_pagecache_reclaimable() works out how many pages are in a state that
zone_reclaim() can reclaim based on the current zone_reclaim_mode. As
part of this, it calculates a delta to the number of unmapped pages. The
code was meant to check delta would not cause underflows and then apply it
but it got accidentally removed.
This patch properly uses delta. It's excessively paranoid at the moment
because it's impossible to underflow but the current form will make future
patches to zone_pagecache_reclaimable() fixing any other scan-heuristic
breakage easier to read and acts as self-documentation reminding authors
of future patches to consider underflow.
This is a fix to patch
vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-reclaim.patch
and they should be merged together.
Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff -puN mm/vmscan.c~vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-reclaim-vmscan-fix-use-of-delta-in-zone_pagecache_reclaimable mm/vmscan.c
--- a/mm/vmscan.c~vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-reclaim-vmscan-fix-use-of-delta-in-zone_pagecache_reclaimable
+++ a/mm/vmscan.c
@@ -2391,7 +2391,11 @@ static long zone_pagecache_reclaimable(s
if (!(zone_reclaim_mode & RECLAIM_WRITE))
delta += zone_page_state(zone, NR_FILE_DIRTY);
- return nr_pagecache_reclaimable;
+ /* Watch for any possible underflows due to delta */
+ if (unlikely(delta > nr_pagecache_reclaimable))
+ delta = nr_pagecache_reclaimable;
+
+ return nr_pagecache_reclaimable - delta;
}
/*
_
Patches currently in -mm which might be from mel@xxxxxxxxx are
origin.patch
linux-next.patch
vmscan-low-order-lumpy-reclaim-also-should-use-pageout_io_sync.patch
mm-alloc_large_system_hash-check-order.patch
page-allocator-replace-__alloc_pages_internal-with-__alloc_pages_nodemask.patch
page-allocator-do-not-sanity-check-order-in-the-fast-path.patch
page-allocator-do-not-sanity-check-order-in-the-fast-path-fix.patch
page-allocator-do-not-check-numa-node-id-when-the-caller-knows-the-node-is-valid.patch
page-allocator-check-only-once-if-the-zonelist-is-suitable-for-the-allocation.patch
page-allocator-break-up-the-allocator-entry-point-into-fast-and-slow-paths.patch
page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath.patch
page-allocator-calculate-the-preferred-zone-for-allocation-only-once.patch
page-allocator-calculate-the-preferred-zone-for-allocation-only-once-fix.patch
page-allocator-calculate-the-migratetype-for-allocation-only-once.patch
page-allocator-calculate-the-alloc_flags-for-allocation-only-once.patch
page-allocator-remove-a-branch-by-assuming-__gfp_high-==-alloc_high.patch
page-allocator-inline-__rmqueue_smallest.patch
page-allocator-inline-buffered_rmqueue.patch
page-allocator-inline-__rmqueue_fallback.patch
page-allocator-do-not-call-get_pageblock_migratetype-more-than-necessary.patch
page-allocator-do-not-disable-interrupts-in-free_page_mlock.patch
page-allocator-do-not-setup-zonelist-cache-when-there-is-only-one-node.patch
page-allocator-do-not-check-for-compound-pages-during-the-page-allocator-sanity-checks.patch
page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark.patch
page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark-replace-the-watermark-related-union-in-struct-zone-with-a-watermark-array.patch
page-allocator-update-nr_free_pages-only-as-necessary.patch
page-allocator-update-nr_free_pages-only-as-necessary-fix.patch
page-allocator-get-the-pageblock-migratetype-without-disabling-interrupts.patch
page-allocator-use-a-pre-calculated-value-instead-of-num_online_nodes-in-fast-paths.patch
page-allocator-use-a-pre-calculated-value-instead-of-num_online_nodes-in-fast-paths-do-not-override-definition-of-node_set_online-with-macro.patch
page-allocator-slab-use-nr_online_nodes-to-check-for-a-numa-platform.patch
page-allocator-move-free_page_mlock-to-page_allocc.patch
page-allocator-sanity-check-order-in-the-page-allocator-slow-path.patch
mm-use-alloc_pages_exact-in-alloc_large_system_hash-to-avoid-duplicated-logic.patch
mm-introduce-pagehuge-for-testing-huge-gigantic-pages-update.patch
page-allocator-warn-if-__gfp_nofail-is-used-for-a-large-allocation.patch
mm-pm-freezer-disable-oom-killer-when-tasks-are-frozen.patch
page-allocator-use-integer-fields-lookup-for-gfp_zone-and-check-for-errors-in-flags-passed-to-the-page-allocator.patch
page-allocator-use-integer-fields-lookup-for-gfp_zone-and-check-for-errors-in-flags-passed-to-the-page-allocator-fix-gfp-zone-patch.patch
page-allocator-clean-up-functions-related-to-pages_min.patch
oom-move-oom_adj-value-from-task_struct-to-mm_struct.patch
oom-avoid-unnecessary-mm-locking-and-scanning-for-oom_disable.patch
oom-invoke-oom-killer-for-__gfp_nofail.patch
page-allocator-clear-n_high_memory-map-before-se-set-it-again.patch
mm-add-a-gfp-translate-script-to-help-understand-page-allocation-failure-reports.patch
mm-add-a-gfp-translate-script-to-help-understand-page-allocation-failure-reports-fix.patch
vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-reclaim.patch
vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-reclaim-vmscan-fix-use-of-delta-in-zone_pagecache_reclaimable.patch
vmscan-properly-account-for-the-number-of-page-cache-pages-zone_reclaim-can-reclaim-mm-fix-documentation-of-min_unmapped_ratio.patch
vmscan-do-not-unconditionally-treat-zones-that-fail-zone_reclaim-as-full.patch
vmscan-count-the-number-of-times-zone_reclaim-scans-and-fails.patch
add-debugging-aid-for-memory-initialisation-problems.patch
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