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authorJan Kara <jack@suse.cz>2014-04-03 14:46:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-03 16:20:49 -0700
commit5acda9d12dcf1ad0d9a5a2a7c646de3472fa7555 (patch)
tree5103d2779fbf2f1f07edb1ed51083d1303073ef9 /mm/backing-dev.c
parent6ca738d60c563d5c6cf6253ee4b8e76fa77b2b9e (diff)
downloadop-kernel-dev-5acda9d12dcf1ad0d9a5a2a7c646de3472fa7555.zip
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bdi: avoid oops on device removal
After commit 839a8e8660b6 ("writeback: replace custom worker pool implementation with unbound workqueue") when device is removed while we are writing to it we crash in bdi_writeback_workfn() -> set_worker_desc() because bdi->dev is NULL. This can happen because even though bdi_unregister() cancels all pending flushing work, nothing really prevents new ones from being queued from balance_dirty_pages() or other places. Fix the problem by clearing BDI_registered bit in bdi_unregister() and checking it before scheduling of any flushing work. Fixes: 839a8e8660b6777e7fe4e80af1a048aebe2b5977 Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Cc: Derek Basehore <dbasehore@chromium.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/backing-dev.c')
-rw-r--r--mm/backing-dev.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index fab8401..09d9591 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -297,7 +297,10 @@ void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
unsigned long timeout;
timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
- queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
+ spin_lock_bh(&bdi->wb_lock);
+ if (test_bit(BDI_registered, &bdi->state))
+ queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
+ spin_unlock_bh(&bdi->wb_lock);
}
/*
@@ -310,9 +313,6 @@ static void bdi_remove_from_list(struct backing_dev_info *bdi)
spin_unlock_bh(&bdi_lock);
synchronize_rcu_expedited();
-
- /* bdi_list is now unused, clear it to mark @bdi dying */
- INIT_LIST_HEAD(&bdi->bdi_list);
}
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
@@ -363,6 +363,11 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
*/
bdi_remove_from_list(bdi);
+ /* Make sure nobody queues further work */
+ spin_lock_bh(&bdi->wb_lock);
+ clear_bit(BDI_registered, &bdi->state);
+ spin_unlock_bh(&bdi->wb_lock);
+
/*
* Drain work list and shutdown the delayed_work. At this point,
* @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
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