Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx> wrote: > On Tue, 2008-12-02 at 13:18 +0900, Tejun Heo wrote: > > > > >>> The other one is a BUG_ON in blk/blk-timeout.c:177 in blk_add_timeout() > > >>> that happens after a few hundred MB of READ_10 traffic, which also > > >>> appears to pass through elv_dequeue_request() at some point: > > >>> > > >>> http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-2.png > > >>> http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-4.png > > > > Hmmm... this means blk_add_timer() is being called after the request > > is already completed. or is it possible since elv_dequeue_request BUG_ON check of queuelist did not trigger a request is on the queuelist with a timeout_list not empty. It would be interesting for a debug run to change the "BUG_ON(!list_empty(&req->timeout_list))" in blk_add_timer to print out the cmd_flags plus req->atomic_flags and also add a "BUG_ON(!list_empty(&rq->timeout_list))" to elv_insert to ensure a request is never added to the queuelist with a timeout_list not empty. > All the problem discovered till now have to do > > with timeout going off without the low level driver knowing about the > > request. I don't have much idea and it'll probably be best to trace > > what's going on using blktrace or printks. > > <nod>, OK. > > > Maybe this is caused by > > list corruption as with the first issue or request completion races > > with requeueing? > > Hrmm, yeah, perhaps the use of scsi_req_map_sg() (which obviously still > has struct bio behind it) is causing the breakage.. I will wait for > Tomo, Boaz and co to have a look at the original patch to > lio-core-2.6.git/drivers/lio-core/target_core_pscsi.c and see if I am > missing something obvious. > > Also, with the previous patch to drivers/scsi/scsi_lib.c(), I am able to > move a few GB of bulk I/O and not hit the BUG_ON in > blk/blk-timeout.c:177 in blk_add_timeout() mentioned above when feeding > struct request into struct scsi_device->request_queue with > blk_execute_rq_nowait() with use_sg > 0 CDBs. However, I am still > running into another reproducable BUG_ON in > block/cfq-iosched.c:cfq_find_next_rq() after extended bulk I/O tests. > -andmike -- Michael Anderson andmike@xxxxxxxxxxxxxxxxxx -- 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
