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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html