The patch titled writeback: prevent duplicate balance_dirty_pages_ratelimited() calls has been added to the -mm tree. Its filename is writeback-prevent-duplicate-balance_dirty_pages_ratelimited-calls.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: writeback: prevent duplicate balance_dirty_pages_ratelimited() calls From: Wu Fengguang <fengguang.wu@xxxxxxxxx> When dd in 512bytes, balance_dirty_pages_ratelimited() used to be called 8 times for the same page, even if the page is only dirtied once. Fix it with a (slightly racy) PageDirty() test. Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> Cc: Chris Mason <chris.mason@xxxxxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Li Shaohua <shaohua.li@xxxxxxxxx> Cc: Theodore Ts'o <tytso@xxxxxxx> Cc: Richard Kennedy <richard@xxxxxxxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Mel Gorman <mel@xxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Michael Rubin <mrubin@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/filemap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff -puN mm/filemap.c~writeback-prevent-duplicate-balance_dirty_pages_ratelimited-calls mm/filemap.c --- a/mm/filemap.c~writeback-prevent-duplicate-balance_dirty_pages_ratelimited-calls +++ a/mm/filemap.c @@ -2255,6 +2255,7 @@ static ssize_t generic_perform_write(str long status = 0; ssize_t written = 0; unsigned int flags = 0; + unsigned int dirty; /* * Copies from kernel address space cannot fail (NFSD is a big user). @@ -2303,6 +2304,7 @@ again: pagefault_enable(); flush_dcache_page(page); + dirty = PageDirty(page); mark_page_accessed(page); status = a_ops->write_end(file, mapping, pos, bytes, copied, page, fsdata); @@ -2329,7 +2331,8 @@ again: pos += copied; written += copied; - balance_dirty_pages_ratelimited(mapping); + if (!dirty) + balance_dirty_pages_ratelimited(mapping); } while (iov_iter_count(i)); _ Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are linux-next.patch writeback-integrated-background-writeback-work.patch writeback-trace-wakeup-event-for-background-writeback.patch writeback-stop-background-kupdate-works-from-livelocking-other-works.patch writeback-stop-background-kupdate-works-from-livelocking-other-works-update.patch writeback-avoid-livelocking-wb_sync_all-writeback.patch writeback-avoid-livelocking-wb_sync_all-writeback-update.patch writeback-check-skipped-pages-on-wb_sync_all.patch writeback-check-skipped-pages-on-wb_sync_all-update.patch writeback-check-skipped-pages-on-wb_sync_all-update-fix.patch writeback-io-less-balance_dirty_pages.patch writeback-consolidate-variable-names-in-balance_dirty_pages.patch writeback-per-task-rate-limit-on-balance_dirty_pages.patch writeback-per-task-rate-limit-on-balance_dirty_pages-fix.patch writeback-prevent-duplicate-balance_dirty_pages_ratelimited-calls.patch writeback-account-per-bdi-accumulated-written-pages.patch writeback-bdi-write-bandwidth-estimation.patch writeback-show-bdi-write-bandwidth-in-debugfs.patch writeback-quit-throttling-when-bdi-dirty-pages-dropped-low.patch writeback-reduce-per-bdi-dirty-threshold-ramp-up-time.patch writeback-make-reasonable-gap-between-the-dirty-background-thresholds.patch writeback-scale-down-max-throttle-bandwidth-on-concurrent-dirtiers.patch writeback-add-trace-event-for-balance_dirty_pages.patch writeback-make-nr_to_write-a-per-file-limit.patch mm-page-writebackc-fix-__set_page_dirty_no_writeback-return-value.patch mm-find_get_pages_contig-fixlet.patch mm-smaps-export-mlock-information.patch memcg-add-page_cgroup-flags-for-dirty-page-tracking.patch memcg-document-cgroup-dirty-memory-interfaces.patch memcg-document-cgroup-dirty-memory-interfaces-fix.patch memcg-create-extensible-page-stat-update-routines.patch memcg-add-lock-to-synchronize-page-accounting-and-migration.patch writeback-create-dirty_info-structure.patch memcg-add-dirty-page-accounting-infrastructure.patch memcg-add-kernel-calls-for-memcg-dirty-page-stats.patch memcg-add-dirty-limits-to-mem_cgroup.patch memcg-add-dirty-limits-to-mem_cgroup-use-native-word-to-represent-dirtyable-pages.patch memcg-add-dirty-limits-to-mem_cgroup-catch-negative-per-cpu-sums-in-dirty-info.patch memcg-add-dirty-limits-to-mem_cgroup-avoid-overflow-in-memcg_hierarchical_free_pages.patch memcg-add-dirty-limits-to-mem_cgroup-correct-memcg_hierarchical_free_pages-return-type.patch memcg-add-dirty-limits-to-mem_cgroup-avoid-free-overflow-in-memcg_hierarchical_free_pages.patch memcg-cpu-hotplug-lockdep-warning-fix.patch memcg-add-cgroupfs-interface-to-memcg-dirty-limits.patch memcg-break-out-event-counters-from-other-stats.patch memcg-check-memcg-dirty-limits-in-page-writeback.patch memcg-use-native-word-page-statistics-counters.patch memcg-use-native-word-page-statistics-counters-fix.patch memcg-add-mem_cgroup-parameter-to-mem_cgroup_page_stat.patch memcg-pass-mem_cgroup-to-mem_cgroup_dirty_info.patch memcg-make-throttle_vm_writeout-memcg-aware.patch memcg-make-throttle_vm_writeout-memcg-aware-fix.patch memcg-simplify-mem_cgroup_page_stat.patch memcg-simplify-mem_cgroup_dirty_info.patch memcg-make-mem_cgroup_page_stat-return-value-unsigned.patch memcg-use-zalloc-rather-than-mallocmemset.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