The patch titled
Subject: mm: memcontrol: clarify migration where old page is uncharged
has been added to the -mm tree. Its filename is
mm-memcontrol-clarify-migration-where-old-page-is-uncharged.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcontrol-clarify-migration-where-old-page-is-uncharged.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcontrol-clarify-migration-where-old-page-is-uncharged.patch
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------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: memcontrol: clarify migration where old page is uncharged
Better explain re-entrant migration when compaction races with reclaim,
and also mention swapcache readahead pages as possible uncharged migration
sources.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff -puN mm/memcontrol.c~mm-memcontrol-clarify-migration-where-old-page-is-uncharged mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcontrol-clarify-migration-where-old-page-is-uncharged
+++ a/mm/memcontrol.c
@@ -6148,7 +6148,12 @@ void mem_cgroup_migrate(struct page *old
if (PageCgroupUsed(pc))
return;
- /* Re-entrant migration: old page already uncharged? */
+ /*
+ * Swapcache readahead pages can get migrated before being
+ * charged, and migration from compaction can happen to an
+ * uncharged page when the PFN walker finds a page that
+ * reclaim just put back on the LRU but has not released yet.
+ */
pc = lookup_page_cgroup(oldpage);
if (!PageCgroupUsed(pc))
return;
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
cgroup-kmemleak-add-kmemleak_free-for-cgroup-deallocations.patch
mm-memcontrol-lockless-page-counters.patch
mm-memcontrol-lockless-page-counters-fix.patch
mm-memcontrol-lockless-page-counters-fix-fix.patch
mm-memcontrol-lockless-page-counters-fix-2.patch
mm-hugetlb_cgroup-convert-to-lockless-page-counters.patch
kernel-res_counter-remove-the-unused-api.patch
kernel-res_counter-remove-the-unused-api-fix.patch
kernel-res_counter-remove-the-unused-api-fix-2.patch
mm-memcontrol-convert-reclaim-iterator-to-simple-css-refcounting.patch
mm-memcontrol-convert-reclaim-iterator-to-simple-css-refcounting-fix.patch
mm-memcontrol-take-a-css-reference-for-each-charged-page.patch
mm-memcontrol-remove-obsolete-kmemcg-pinning-tricks.patch
mm-memcontrol-continue-cache-reclaim-from-offlined-groups.patch
mm-memcontrol-remove-synchroneous-stock-draining-code.patch
mm-vmscan-count-only-dirty-pages-as-congested.patch
memcg-simplify-unreclaimable-groups-handling-in-soft-limit-reclaim.patch
mm-memcontrol-update-mem_cgroup_page_lruvec-documentation.patch
mm-memcontrol-clarify-migration-where-old-page-is-uncharged.patch
mm-memcontrol-uncharge-pages-on-swapout.patch
mm-memcontrol-remove-unnecessary-pcg_memsw-memoryswap-charge-flag.patch
mm-memcontrol-remove-unnecessary-pcg_mem-memory-charge-flag.patch
mm-memcontrol-remove-unnecessary-pcg_used-pc-mem_cgroup-valid-flag.patch
debugging-keep-track-of-page-owners.patch
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