On Thu, Jan 18 2018 at 3:58P -0500, Bart Van Assche <Bart.VanAssche@xxxxxxx> wrote: > On Thu, 2018-01-18 at 15:48 -0500, Mike Snitzer wrote: > > For Bart's test the underlying scsi-mq driver is what is regularly > > hitting this case in __blk_mq_try_issue_directly(): > > > > if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) > > Hello Mike, > > That code path is not the code path that triggered the lockups that I reported > during the past days. If you're hitting blk_mq_sched_insert_request() then you most certainly are hitting that code path. If you aren't then what was your earlier email going on about? https://www.redhat.com/archives/dm-devel/2018-January/msg00372.html If you were just focusing on that as one possible reason, that isn't very helpful. By this point you really should _know_ what is triggering the stall based on the code paths taken. Please use ftrace's function_graph tracer if need be. > These lockups were all triggered by incorrect handling of > .queue_rq() returning BLK_STS_RESOURCE. Please be precise, dm_mq_queue_rq()'s return of BLK_STS_RESOURCE? "Incorrect" because it no longer runs blk_mq_delay_run_hw_queue()? Please try to do more work analyzing the test case that only you can easily run (due to srp_test being a PITA). And less time lobbying for a change that you don't understand to _really_ be correct. We have time to get this right, please stop hyperventilating about "regressions". Thanks, Mike
