On 8/18/20 10:49 PM, Sarah Newman wrote:
The other place that drbd_send_acks_wf was called from already
calls kref_get.
This can be reproduced with the following for an existing
connection:
drbdsetup net-options local_addr remote_addr \
--protocol=C \
--allow-two-primaries
drbsetup primary minor
dd if=/dev/drbd<minor> of=sector bs=512 count=1
while true; do dd if=sector of=/dev/drbd<minor>; done
During this, if we have function tracing enabled for e_send_superseded, it
triggers:
$ sudo cat /sys/kernel/tracing/trace_pipe
kworker/u4:2-14838 [001] .... 113244.465689: e_send_superseded <-drbd_finish_peer_reqs
kworker/u4:2-14838 [001] .... 113244.468237: e_send_superseded <-drbd_finish_peer_reqs
kworker/u4:2-14838 [001] .... 113244.482757: e_send_superseded <-drbd_finish_peer_reqs
kworker/u4:1-15502 [001] .... 113244.485092: e_send_superseded <-drbd_finish_peer_reqs
This eventually results in behavior like:
[113418.435846] watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [dd:15505]
Or a message similar to
block drbd0: ASSERT( device->open_cnt == 0 )
in drivers/block/drbd/drbd_main.c:2232
Signed-off-by: Sarah Newman <srn@xxxxxxxxx>
---
drivers/block/drbd/drbd_receiver.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 2b3103c30857..1ad693a5aab5 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -2531,7 +2531,11 @@ static int handle_write_conflicts(struct drbd_device *device,
peer_req->w.cb = superseded ? e_send_superseded :
e_send_retry_write;
list_add_tail(&peer_req->w.list, &device->done_ee);
- queue_work(connection->ack_sender, &peer_req->peer_device->send_acks_work);
+ /* put is in drbd_send_acks_wf() */
+ kref_get(&device->kref);
+ if (!queue_work(connection->ack_sender,
+ &peer_req->peer_device->send_acks_work))
+ kref_put(&device->kref, drbd_destroy_device);
err = -ENOENT;
goto out;
Added linux-block as a CC. I can resend this patch if necessary.
Checking in to see if any changes or additional testing is required for this patch before it's accepted.
Thanks, Sarah
