As the comment above rq_completed() explains, md members must not be touched after the dm_put() at the end of that function has been invoked. Avoid that the md->queue can be run asynchronously after the last md reference has been dropped by running that queue synchronously. This patch fixes the following kernel oops: general protection fault: 0000 [#1] SMP RIP: 0010:[<ffffffff810fe754>] [<ffffffff810fe754>] mempool_free+0x24/0xb0 Call Trace: <IRQ> [<ffffffff81187417>] bio_put+0x97/0xc0 [<ffffffffa02247a5>] end_clone_bio+0x35/0x90 [dm_mod] [<ffffffff81185efd>] bio_endio+0x1d/0x30 [<ffffffff811f03a3>] req_bio_endio.isra.51+0xa3/0xe0 [<ffffffff811f2f68>] blk_update_request+0x118/0x520 [<ffffffff811f3397>] blk_update_bidi_request+0x27/0xa0 [<ffffffff811f343c>] blk_end_bidi_request+0x2c/0x80 [<ffffffff811f34d0>] blk_end_request+0x10/0x20 [<ffffffffa000b32b>] scsi_io_completion+0xfb/0x6c0 [scsi_mod] [<ffffffffa000107d>] scsi_finish_command+0xbd/0x120 [scsi_mod] [<ffffffffa000b12f>] scsi_softirq_done+0x13f/0x160 [scsi_mod] [<ffffffff811f9fd0>] blk_done_softirq+0x80/0xa0 [<ffffffff81044551>] __do_softirq+0xf1/0x250 [<ffffffff8142ee8c>] call_softirq+0x1c/0x30 [<ffffffff8100420d>] do_softirq+0x8d/0xc0 [<ffffffff81044885>] irq_exit+0xd5/0xe0 [<ffffffff8142f3e3>] do_IRQ+0x63/0xe0 [<ffffffff814257af>] common_interrupt+0x6f/0x6f <EOI> [<ffffffffa021737c>] srp_queuecommand+0x8c/0xcb0 [ib_srp] [<ffffffffa0002f18>] scsi_dispatch_cmd+0x148/0x310 [scsi_mod] [<ffffffffa000a38e>] scsi_request_fn+0x31e/0x520 [scsi_mod] [<ffffffff811f1e57>] __blk_run_queue+0x37/0x50 [<ffffffff811f1f69>] blk_delay_work+0x29/0x40 [<ffffffff81059003>] process_one_work+0x1c3/0x5c0 [<ffffffff8105b22e>] worker_thread+0x15e/0x440 [<ffffffff8106164b>] kthread+0xdb/0xe0 [<ffffffff8142db9c>] ret_from_fork+0x7c/0xb0 Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> Cc: Alasdair G Kergon <agk@xxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: Mike Snitzer <snitzer@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: James Bottomley <JBottomley@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> --- drivers/md/dm.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 314a0e2..0218fc3 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -729,13 +729,13 @@ static void rq_completed(struct mapped_device *md, int rw, int run_queue) 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. + * Although this function may be invoked indirectly from inside + * blk_run_queue(), invoking blk_run_queue() here is safe because that + * function returns immediately when it detects that it has been + * called recursively. */ if (run_queue) - blk_run_queue_async(md->queue); + blk_run_queue(md->queue); /* * dm_put() must be at the end of this function. See the comment above -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
