On Thu, Feb 02 2017 at 2:46pm -0500, Bart Van Assche <Bart.VanAssche@xxxxxxxxxxx> wrote: > On Thu, 2017-02-02 at 14:13 -0500, Mike Snitzer wrote: > > On Thu, Feb 02 2017 at 1:43pm -0500, Bart Van Assche <Bart.VanAssche@xxxxxxxxxxx> wrote: > > > On Thu, 2017-02-02 at 13:33 -0500, Mike Snitzer wrote: > > > > I'll go back over hch's changes to see if I can spot anything. But is > > > > this testing using dm_mod.use_bk_mq=Y or are you testing old .request_fn > > > > dm-multipath? > > > > > > The srp-test software tests multiple configurations: dm-mq on scsi-mq, dm-sq > > > on scsi-mq and dm-sq on scsi-sq. I have not yet checked which of these > > > three configurations triggers the kernel crash. > > > > OK, such info is important to provide for crashes like this. Please let > > me know once you do. > > Hello Mike, > > Apparently it's the large I/O test (using dm-mq on scsi-mq) that triggers the > crash: I've gone over Christoph's "dm: always defer request allocation to the owner of the request_queue" commit yet again. Most of that commit's changes are just mechanical. I didn't see any problems. In general, dm_start_request() calls dm_get(md) to take a reference on the mapped_device. And rq_completed() calls dm_put(md) to drop the reference. The DM device's request_queue (md->queue) should _not_ ever be torn down before all references on the md have been dropped. But I'll have to look closer on how/if that is enforced anywhere by coordinating with block core. In any case, the crash you reported was that the mapped_device was being dereferenced after it was freed (at line 187's md->queue). Which seems to imply a dm_get/dm_put reference count regression. But I'm not seeing where at this point. > # ~bart/software/infiniband/srp-test/run_tests -r 10 > [ ... ] > Test /home/bart/software/infiniband/srp-test/tests/02-sq-on-mq succeeded > Running test /home/bart/software/infiniband/srp-test/tests/03 ... > Test large transfer sizes with cmd_sg_entries=255 > removing /dev/mapper/mpatht: [ CRASH ] > > The source code of the test I ran is available at > https://github.com/bvanassche/srp-test. Any progress on getting this to work without requiring infiniband HW? -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
