The patch titled vmscan: fix zone shrinking exit when scan work is done has been added to the -mm tree. Its filename is vmscan-fix-zone-shrinking-exit-when-scan-work-is-done.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 *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: vmscan: fix zone shrinking exit when scan work is done From: Johannes Weiner <hannes@xxxxxxxxxxx> 3e7d344 ("mm: vmscan: reclaim order-0 and use compaction instead of lumpy reclaim") introduced an indefinite loop in shrink_zone(). It meant to break out of this loop when no pages had been reclaimed and not a single page was even scanned. The way it would detect the latter is by taking a snapshot of sc->nr_scanned at the beginning of the function and comparing it against the new sc->nr_scanned after the scan loop. But it would re-iterate without updating that snapshot, looping forever if sc->nr_scanned changed at least once since shrink_zone() was invoked. This is not the sole condition that would exit that loop, but it requires other processes to change the zone state, as the reclaimer that is stuck obviously can not anymore. This is only happening for higher-order allocations, where reclaim is run back to back with compaction. Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Reported-by: Michal Hocko <mhocko@xxxxxxx> Tested-by: Kent Overstreet<kent.overstreet@xxxxxxxxx> Reported-by: Kent Overstreet <kent.overstreet@xxxxxxxxx> Acked-by: Mel Gorman <mel@xxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN mm/vmscan.c~vmscan-fix-zone-shrinking-exit-when-scan-work-is-done mm/vmscan.c --- a/mm/vmscan.c~vmscan-fix-zone-shrinking-exit-when-scan-work-is-done +++ a/mm/vmscan.c @@ -1882,12 +1882,12 @@ static void shrink_zone(int priority, st unsigned long nr[NR_LRU_LISTS]; unsigned long nr_to_scan; enum lru_list l; - unsigned long nr_reclaimed; + unsigned long nr_reclaimed, nr_scanned; unsigned long nr_to_reclaim = sc->nr_to_reclaim; - unsigned long nr_scanned = sc->nr_scanned; restart: nr_reclaimed = 0; + nr_scanned = sc->nr_scanned; get_scan_count(zone, sc, nr, priority); while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || _ Patches currently in -mm which might be from hannes@xxxxxxxxxxx are vmscan-fix-zone-shrinking-exit-when-scan-work-is-done.patch mm-introduce-delete_from_page_cache.patch mm-hugetlbfs-change-remove_from_page_cache.patch mm-shmem-change-remove_from_page_cache.patch mm-truncate-change-remove_from_page_cache.patch mm-good-bye-remove_from_page_cache.patch mm-change-__remove_from_page_cache.patch epoll-fix-compiler-warning-and-optimize-the-non-blocking-path-fix.patch memcg-res_counter_read_u64-fix-potential-races-on-32-bit-machines.patch memcg-fix-ugly-initialization-of-return-value-is-in-caller.patch memcg-soft-limit-reclaim-should-end-at-limit-not-below.patch memcg-simplify-the-way-memory-limits-are-checked.patch memcg-remove-unused-page-flag-bitfield-defines.patch memcg-remove-impossible-conditional-when-committing.patch memcg-remove-null-check-from-lookup_page_cgroup-result.patch memcg-add-memcg-sanity-checks-at-allocating-and-freeing-pages.patch memcg-add-memcg-sanity-checks-at-allocating-and-freeing-pages-update.patch memcg-no-uncharged-pages-reach-page_cgroup_zoneinfo.patch memcg-change-page_cgroup_zoneinfo-signature.patch memcg-fold-__mem_cgroup_move_account-into-caller.patch memcg-condense-page_cgroup-to-page-lookup-points.patch memcg-remove-direct-page_cgroup-to-page-pointer.patch memcg-remove-direct-page_cgroup-to-page-pointer-fix.patch memcg-remove-direct-page_cgroup-to-page-pointer-fix-fix.patch crash_dump-export-is_kdump_kernel-to-modules-consolidate-elfcorehdr_addr-setup_elfcorehdr-and-saved_max_pfn.patch crash_dump-export-is_kdump_kernel-to-modules-consolidate-elfcorehdr_addr-setup_elfcorehdr-and-saved_max_pfn-fix.patch crash_dump-export-is_kdump_kernel-to-modules-consolidate-elfcorehdr_addr-setup_elfcorehdr-and-saved_max_pfn-fix-fix.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