Hello Mike, If I trigger failover and failback with kernel v4.8-rc2 and ib_srp then I see the following: BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 IP: [<ffffffff8130d03b>] blk_mq_insert_request+0x3b/0xc0 CPU: 4 PID: 12606 Comm: kdmwork-254:1 Not tainted 4.8.0-rc2-dbg+ #1 Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.0.2 11/17/2014 task: ffff880363d3e240 task.stack: ffff8803618ac000 RIP: 0010:[<ffffffff8130d03b>] [<ffffffff8130d03b>] blk_mq_insert_request+0x3b/0xc0 Call Trace: [<ffffffff81300da9>] blk_insert_cloned_request+0xa9/0x1e0 [<ffffffffa04302f0>] map_request+0x190/0x2d0 [dm_mod] [<ffffffffa043044d>] map_tio_request+0x1d/0x40 [dm_mod] [<ffffffff81087101>] kthread_worker_fn+0xd1/0x1b0 [<ffffffff81086fba>] kthread+0xea/0x100 [<ffffffff8162d53f>] ret_from_fork+0x1f/0x40 (gdb) list *(blk_mq_insert_request+0x3b) 0xffffffff8130d03b is in blk_mq_insert_request (block/blk-mq.c:1078). 1073 struct request_queue *q = rq->q; 1074 struct blk_mq_hw_ctx *hctx; 1075 struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx; 1076 1077 current_ctx = blk_mq_get_ctx(q); 1078 if (!cpu_online(ctx->cpu)) 1079 rq->mq_ctx = ctx = current_ctx; 1080 1081 hctx = q->mq_ops->map_queue(q, ctx->cpu); 1082 (gdb) print &((struct blk_mq_ctx*)0)->cpu $1 = (unsigned int *) 0x80 I think this means that ctx->cpu == NULL was hit. This was observed with the same test software and configuration I used for my kernel v4.7 tests (CONFIG_SCSI_MQ_DEFAULT=y and CONFIG_DM_MQ_DEFAULT=n). The above callstack was not observed while testing kernel v4.7. Can you have a look at this? Thanks, Bart. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
