The patch titled
writeback: stop background/kupdate works from livelocking other works
has been added to the -mm tree. Its filename is
writeback-stop-background-kupdate-works-from-livelocking-other-works.patch
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------------------------------------------------------
Subject: writeback: stop background/kupdate works from livelocking other works
From: Jan Kara <jack@xxxxxxx>
Background writeback are easily livelockable (from a definition of their
target). This is inconvenient because it can make sync(1) stall forever
waiting on its queued work to be finished. Generally, when a flusher
thread has some work queued, someone submitted the work to achieve a goal
more specific than what background writeback does. So it makes sense to
give it a priority over a generic page cleaning.
Thus we interrupt background writeback if there is some other work to do.
We return to the background writeback after completing all the queued
work.
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Jan Engelhardt <jengelh@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN fs/fs-writeback.c~writeback-stop-background-kupdate-works-from-livelocking-other-works fs/fs-writeback.c
--- a/fs/fs-writeback.c~writeback-stop-background-kupdate-works-from-livelocking-other-works
+++ a/fs/fs-writeback.c
@@ -651,6 +651,15 @@ static long wb_writeback(struct bdi_writ
break;
/*
+ * Background writeout and kupdate-style writeback are
+ * easily livelockable. Stop them if there is other work
+ * to do so that e.g. sync can proceed.
+ */
+ if ((work->for_background || work->for_kupdate) &&
+ !list_empty(&wb->bdi->work_list))
+ break;
+
+ /*
* For background writeout, stop when we are below the
* background dirty threshold
*/
_
Patches currently in -mm which might be from jack@xxxxxxx are
origin.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-avoid-livelocking-wb_sync_all-writeback.patch
writeback-check-skipped-pages-on-wb_sync_all.patch
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