On Wed, Jun 27, 2018 at 12:55:18PM -0700, Bart Van Assche wrote:

This patch avoids that removing a path controlled by the dm-mpath driver while mkfs is running triggers the following kernel bug:

kernel BUG at block/blk-core.c:3347!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 20 PID: 24369 Comm: mkfs.ext4 Not tainted 4.18.0-rc1-dbg+ #2
RIP: 0010:blk_end_request_all+0x68/0x70
Call Trace:
 <IRQ>
 dm_softirq_done+0x326/0x3d0 [dm_mod]
 blk_done_softirq+0x19b/0x1e0
 __do_softirq+0x128/0x60d
 irq_exit+0x100/0x110
 smp_call_function_single_interrupt+0x90/0x330
 call_function_single_interrupt+0xf/0x20
 </IRQ>

Fixes: f9d03f96b988 ("block: improve handling of the magic discard payload") Signed-off-by: Bart Van Assche bart.vanassche@wdc.com Cc: Christoph Hellwig hch@lst.de Cc: Mike Snitzer snitzer@redhat.com Cc: Ming Lei ming.lei@redhat.com Cc: Hannes Reinecke hare@suse.com Cc: Johannes Thumshirn jthumshirn@suse.de Cc: stable@vger.kernel.org

---

block/blk-core.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c index 118dd17eb71f..f1e07ed1513c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -3529,6 +3529,10 @@ static void __blk_rq_prep_clone(struct request *dst, struct request *src) dst->cpu = src->cpu; dst->__sector = blk_rq_pos(src); dst->__data_len = blk_rq_bytes(src);

• if (src->rq_flags & RQF_SPECIAL_PAYLOAD) {

• dst->rq_flags |= RQF_SPECIAL_PAYLOAD;
  

• dst->special_vec = src->special_vec;
  

• } dst->nr_phys_segments = src->nr_phys_segments; dst->ioprio = src->ioprio; dst->extra_len = src->extra_len;

-- 2.17.1

Reviewed-by: Ming Lei ming.lei@redhat.com

BTW, if possible, could you please make a block test to catch this issue?

thanks, Ming