The patch titled
writeback: update dirtied_when for synced inode to prevent livelock
has been added to the -mm tree. Its filename is
writeback-update-dirtied_when-for-synced-inode-to-prevent-livelock.patch
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------------------------------------------------------
Subject: writeback: update dirtied_when for synced inode to prevent livelock
From: Wu Fengguang <fengguang.wu@xxxxxxxxx>
With the more aggressive "keep writeback as long as we wrote something"
logic in wb_writeback(), the "use LONG_MAX .nr_to_write" trick in commit
b9543dac5bbc ("writeback: avoid livelocking WB_SYNC_ALL writeback") is no
longer enough to stop sync livelock.
The fix is to explicitly update .dirtied_when on synced inodes, so that
they are no longer considered for writeback in the next round.
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN fs/fs-writeback.c~writeback-update-dirtied_when-for-synced-inode-to-prevent-livelock fs/fs-writeback.c
--- a/fs/fs-writeback.c~writeback-update-dirtied_when-for-synced-inode-to-prevent-livelock
+++ a/fs/fs-writeback.c
@@ -431,6 +431,15 @@ writeback_single_inode(struct inode *ino
requeue_io(inode, wb);
} else {
/*
+ * sync livelock prevention: each inode is
+ * tagged and synced in one shot. If still
+ * dirty, move it back to s_dirty with updated
+ * dirty time to prevent syncing it again.
+ */
+ if (wbc->sync_mode == WB_SYNC_ALL ||
+ wbc->tagged_sync)
+ inode->dirtied_when = jiffies;
+ /*
* Writeback blocked by something other than
* congestion. Delay the inode for some time to
* avoid spinning on the CPU (100% iowait)
_
Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are
mm-per-node-vmstat-show-proper-vmstats.patch
mm-per-node-vmstat-show-proper-vmstats-fix.patch
writeback-pass-writeback_control-down-to-move_expired_inodes.patch
writeback-introduce-writeback_controlinodes_cleaned.patch
writeback-try-more-writeback-as-long-as-something-was-written.patch
writeback-the-kupdate-expire-timestamp-should-be-a-moving-target.patch
writeback-sync-expired-inodes-first-in-background-writeback.patch
writeback-sync-expired-inodes-first-in-background-writeback-fix.patch
writeback-refill-b_io-iff-empty.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix-fix.patch
writeback-split-inode_wb_list_lock-into-bdi_writebacklist_lock-fix-fix-fix.patch
writeback-elevate-queue_io-into-wb_writeback.patch
writeback-introduce-wbctagged_sync-for-the-wb_sync_none-sync-stage.patch
writeback-update-dirtied_when-for-synced-inode-to-prevent-livelock.patch
writeback-avoid-extra-sync-work-at-enqueue-time.patch
readahead-readahead-page-allocations-are-ok-to-fail.patch
readahead-return-early-when-readahead-is-disabled.patch
readahead-reduce-unnecessary-mmap_miss-increases.patch
readahead-trigger-mmap-sequential-readahead-on-pg_readahead.patch
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