• Omar Sandoval's avatar
    block: only call sched requeue_request() for scheduled requests · e8a8a185
    Omar Sandoval authored
    Yang Yang reported the following crash caused by requeueing a flush
    request in Kyber:
    
      [    2.517297] Unable to handle kernel paging request at virtual address ffffffd8071c0b00
      ...
      [    2.517468] pc : clear_bit+0x18/0x2c
      [    2.517502] lr : sbitmap_queue_clear+0x40/0x228
      [    2.517503] sp : ffffff800832bc60 pstate : 00c00145
      ...
      [    2.517599] Process ksoftirqd/5 (pid: 51, stack limit = 0xffffff8008328000)
      [    2.517602] Call trace:
      [    2.517606]  clear_bit+0x18/0x2c
      [    2.517619]  kyber_finish_request+0x74/0x80
      [    2.517627]  blk_mq_requeue_request+0x3c/0xc0
      [    2.517637]  __scsi_queue_insert+0x11c/0x148
      [    2.517640]  scsi_softirq_done+0x114/0x130
      [    2.517643]  blk_done_softirq+0x7c/0xb0
      [    2.517651]  __do_softirq+0x208/0x3bc
      [    2.517657]  run_ksoftirqd+0x34/0x60
      [    2.517663]  smpboot_thread_fn+0x1c4/0x2c0
      [    2.517667]  kthread+0x110/0x120
      [    2.517669]  ret_from_fork+0x10/0x18
    
    This happens because Kyber doesn't track flush requests, so
    kyber_finish_request() reads a garbage domain token. Only call the
    scheduler's requeue_request() hook if RQF_ELVPRIV is set (like we do for
    the finish_request() hook in blk_mq_free_request()). Now that we're
    handling it in blk-mq, also remove the check from BFQ.
    Reported-by: default avatarYang Yang <yang.yang@vivo.com>
    Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    e8a8a185
bfq-iosched.c 236 KB