On Tue, Apr 28 2015 at 7:52am -0400, Bart Van Assche <bart.vanassche@xxxxxxxxxxx> wrote: > Hello, > > Earlier today I started testing an SRP initiator patch series on top > of Linux kernel v4.1-rc1. Although that patch series works reliably > on top of kernel v4.0, a test during which I triggered > scsi_remove_host() + relogin (for p in > /sys/class/srp_remote_ports/*; do echo 1 >$p/delete & done; wait; > srp_daemon -oaec) triggered the following kernel oops: > > device-mapper: multipath: Failing path 8:0. > BUG: unable to handle kernel NULL pointer dereference at 0000000000000138 > IP: [<ffffffffa045f8e9>] free_rq_clone+0x29/0xb0 [dm_mod] ... > In case anyone wants to see the translation of the crash address: > > (gdb) list *(free_rq_clone+0x29) > 0x919 is in free_rq_clone (drivers/md/dm.c:1092). > 1087 struct dm_rq_target_io *tio = clone->end_io_data; > 1088 struct mapped_device *md = tio->md; > 1089 > 1090 blk_rq_unprep_clone(clone); > 1091 > 1092 if (clone->q->mq_ops) > 1093 tio->ti->type->release_clone_rq(clone); > 1094 else if (!md->queue->mq_ops) > 1095 /* request_fn queue stacked on request_fn > queue(s) */ > 1096 free_clone_request(md, clone); I saw a crash like this yesterday with 4.1-rc1 (definitely due to clone->q being NULL) but I didn't get a full backtrace over serial console so I cannot be sure it is exactly like yours. In my case I was using hch's lio-utils based test setup that he documented here: https://www.redhat.com/archives/dm-devel/2015-April/msg00138.html But I got the crash the first time I ran this script: multipathd -F tcm_loop --unload tcm_node --freedev iblock_0/array Rough first experience with LIO ;) So I just chalked it up to tcm_loop or something not being careful about device lifetime. So we now have 2 data points (each using different storage backend). I haven't been able to reproduce the issue again though -- but I switch away from using multipathd to create the multipath device and resorted to using dmsetup directly (with a dmsetup remove for cleanup instead of multipath -F). -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
