This is a note to let you know that I've just added the patch titled
writeback: fix memory leak in wb_queue_work()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
writeback-fix-memory-leak-in-wb_queue_work.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Dec 18 14:12:34 CET 2017
From: Tahsin Erdogan <tahsin@xxxxxxxxxx>
Date: Fri, 10 Mar 2017 12:09:49 -0800
Subject: writeback: fix memory leak in wb_queue_work()
From: Tahsin Erdogan <tahsin@xxxxxxxxxx>
[ Upstream commit 4a3a485b1ed0e109718cc8c9d094fa0f552de9b2 ]
When WB_registered flag is not set, wb_queue_work() skips queuing the
work, but does not perform the necessary clean up. In particular, if
work->auto_free is true, it should free the memory.
The leak condition can be reprouced by following these steps:
mount /dev/sdb /mnt/sdb
/* In qemu console: device_del sdb */
umount /dev/sdb
Above will result in a wb_queue_work() call on an unregistered wb and
thus leak memory.
Reported-by: John Sperbeck <jsperbeck@xxxxxxxxxx>
Signed-off-by: Tahsin Erdogan <tahsin@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -173,19 +173,33 @@ static void wb_wakeup(struct bdi_writeba
spin_unlock_bh(&wb->work_lock);
}
+static void finish_writeback_work(struct bdi_writeback *wb,
+ struct wb_writeback_work *work)
+{
+ struct wb_completion *done = work->done;
+
+ if (work->auto_free)
+ kfree(work);
+ if (done && atomic_dec_and_test(&done->cnt))
+ wake_up_all(&wb->bdi->wb_waitq);
+}
+
static void wb_queue_work(struct bdi_writeback *wb,
struct wb_writeback_work *work)
{
trace_writeback_queue(wb, work);
- spin_lock_bh(&wb->work_lock);
- if (!test_bit(WB_registered, &wb->state))
- goto out_unlock;
if (work->done)
atomic_inc(&work->done->cnt);
- list_add_tail(&work->list, &wb->work_list);
- mod_delayed_work(bdi_wq, &wb->dwork, 0);
-out_unlock:
+
+ spin_lock_bh(&wb->work_lock);
+
+ if (test_bit(WB_registered, &wb->state)) {
+ list_add_tail(&work->list, &wb->work_list);
+ mod_delayed_work(bdi_wq, &wb->dwork, 0);
+ } else
+ finish_writeback_work(wb, work);
+
spin_unlock_bh(&wb->work_lock);
}
@@ -1875,16 +1889,9 @@ static long wb_do_writeback(struct bdi_w
set_bit(WB_writeback_running, &wb->state);
while ((work = get_next_work_item(wb)) != NULL) {
- struct wb_completion *done = work->done;
-
trace_writeback_exec(wb, work);
-
wrote += wb_writeback(wb, work);
-
- if (work->auto_free)
- kfree(work);
- if (done && atomic_dec_and_test(&done->cnt))
- wake_up_all(&wb->bdi->wb_waitq);
+ finish_writeback_work(wb, work);
}
/*
Patches currently in stable-queue which might be from tahsin@xxxxxxxxxx are
queue-4.9/writeback-fix-memory-leak-in-wb_queue_work.patch