Commit 08802ed6 authored Dec 05, 2019 by Hou Tao Committed by Jens Axboe Dec 05, 2019

bfq-iosched: Ensure bio->bi_blkg is valid before using it



bio->bi_blkg will be NULL when the issue of the request
has bypassed the block layer as shown in the following oops:

 Internal error: Oops: 96000005 [#1] SMP
 CPU: 17 PID: 2996 Comm: scsi_id Not tainted 5.4.0 #4
 Call trace:
  percpu_counter_add_batch+0x38/0x4c8
  bfqg_stats_update_legacy_io+0x9c/0x280
  bfq_insert_requests+0xbac/0x2190
  blk_mq_sched_insert_request+0x288/0x670
  blk_execute_rq_nowait+0x140/0x178
  blk_execute_rq+0x8c/0x140
  sg_io+0x604/0x9c0
  scsi_cmd_ioctl+0xe38/0x10a8
  scsi_cmd_blk_ioctl+0xac/0xe8
  sd_ioctl+0xe4/0x238
  blkdev_ioctl+0x590/0x20e0
  block_ioctl+0x60/0x98
  do_vfs_ioctl+0xe0/0x1b58
  ksys_ioctl+0x80/0xd8
  __arm64_sys_ioctl+0x40/0x78
  el0_svc_handler+0xc4/0x270

so ensure its validity before using it.

Fixes: fd41e603 ("bfq-iosched: stop using blkg->stat_bytes and ->stat_ios")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 08bdcc35

block/bfq-cgroup.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -351,6 +351,9 @@ void bfqg_stats_update_legacy_io(struct request_queue q, struct request rq)
		{
		struct bfq_group *bfqg = blkg_to_bfqg(rq->bio->bi_blkg);

		if (!bfqg)
		return;

		blkg_rwstat_add(&bfqg->stats.bytes, rq->cmd_flags, blk_rq_bytes(rq));
		blkg_rwstat_add(&bfqg->stats.ios, rq->cmd_flags, 1);
		}

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