Hello Paolo, If I enable the BFQ scheduler for a dm-mpath device then a kernel oops appears (see also below). This happens systematically with Linus' tree from this morning (commit 54ce685cae30) merged with Jens' for-linus branch (commit a78773906147 ("block, bfq: add requeue-request hook")) and for-next branch (commit 88455ad7f928). Is this a known issue?
Thanks, Bart. BUG: unable to handle kernel NULL pointer dereference at 0000000000000200 IP: rb_erase+0x284/0x380 PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP CPU: 1 PID: 0 Comm: swapper/1 Tainted: G W 4.15.0-dbg+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 RIP: 0010:rb_erase+0x284/0x380 Call Trace: <IRQ> elv_rb_del+0x20/0x30 bfq_remove_request+0x8d/0x2e0 [bfq] bfq_finish_requeue_request+0x2bb/0x390 [bfq] blk_mq_free_request+0x51/0x170 dm_softirq_done+0xd5/0x240 [dm_mod] flush_smp_call_function_queue+0x92/0x140 smp_call_function_single_interrupt+0x47/0x2b0 call_function_single_interrupt+0xa2/0xb0 </IRQ>