Messages in this thread Patch in this message | | | Subject | Re: INFO: task hung in wb_shutdown (2) | From | Tetsuo Handa <> | Date | Tue, 24 Apr 2018 21:19:54 +0900 |
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From 39ed6be8a2c12dfe54feaa5abbc2ec46103022bf Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Date: Tue, 24 Apr 2018 11:59:08 +0900 Subject: [PATCH] bdi: wake up concurrent wb_shutdown() callers.
syzbot is reporting hung tasks at wait_on_bit(WB_shutting_down) in wb_shutdown() [1]. This might be because commit 5318ce7d46866e1d ("bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") forgot to call wake_up_bit(WB_shutting_down) after clear_bit(WB_shutting_down).
[1] https://syzkaller.appspot.com/bug?id=b297474817af98d5796bc544e1bb806fc3da0e5e
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+c0cf869505e03bdf1a24@syzkaller.appspotmail.com> Fixes: 5318ce7d46866e1d ("bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") Cc: Tejun Heo <tj@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@fb.com> --- mm/backing-dev.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 023190c..dadac99 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -384,6 +384,8 @@ static void wb_shutdown(struct bdi_writeback *wb) */ smp_wmb(); clear_bit(WB_shutting_down, &wb->state); + smp_mb(); /* advised by wake_up_bit() */ + wake_up_bit(&wb->state, WB_shutting_down); } static void wb_exit(struct bdi_writeback *wb) -- 1.8.3.1
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