This is a note to let you know that I've just added the patch titled
dm: fix deadlock with request based dm and queue request_fn recursion
to the 3.0-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:
dm-fix-deadlock-with-request-based-dm-and-queue-request_fn-recursion.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From a8c32a5c98943d370ea606a2e7dc04717eb92206 Mon Sep 17 00:00:00 2001
From: Jens Axboe <[email protected]>
Date: Tue, 6 Nov 2012 12:24:26 +0100
Subject: dm: fix deadlock with request based dm and queue request_fn recursion
From: Jens Axboe <[email protected]>
commit a8c32a5c98943d370ea606a2e7dc04717eb92206 upstream.
Request based dm attempts to re-run the request queue off the
request completion path. If used with a driver that potentially does
end_io from its request_fn, we could deadlock trying to recurse
back into request dispatch. Fix this by punting the request queue
run to kblockd.
Tested to fix a quickly reproducible deadlock in such a scenario.
Acked-by: Alasdair G Kergon <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/md/dm.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -745,8 +745,14 @@ static void rq_completed(struct mapped_d
if (!md_in_flight(md))
wake_up(&md->wait);
+ /*
+ * Run this off this callpath, as drivers could invoke end_io while
+ * inside their request_fn (and holding the queue lock). Calling
+ * back into ->request_fn() could deadlock attempting to grab the
+ * queue lock again.
+ */
if (run_queue)
- blk_run_queue(md->queue);
+ blk_run_queue_async(md->queue);
/*
* dm_put() must be at the end of this function. See the comment above
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/drivers-block-dac960-fix-dac960_v2_ioctl_opcode_t-wenum-compare-warning.patch
queue-3.0/drivers-block-dac960-fix-wuninitialized-warning.patch
queue-3.0/dm-fix-deadlock-with-request-based-dm-and-queue-request_fn-recursion.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
