Re: [PATCH v2 0/3] blk-cgroup: some cleanup

[Bart Van Assche]

On 4/6/23 07:50, Chengming Zhou wrote:
> These are some cleanup patches of blk-cgroup. Thanks for review.

With these patches applied, my kernel test VM crashes during boot. The 
following crash disappears if I revert these patches:

BUG: KASAN: null-ptr-deref in bio_associate_blkg_from_css+0x83/0x240
Read of size 8 at addr 0000000000000518 by task blkid/5885
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 
1.16.0-debian-1.16.0-5 04/01/2014
Call Trace:
 dump_stack_lvl+0x4a/0x80
 print_report+0x21e/0x260
 kasan_report+0xc2/0xf0
 __asan_load8+0x69/0x90
 bio_associate_blkg_from_css+0x83/0x240
 bfq_bio_bfqg+0xce/0x120 [bfq]
 bfq_bic_update_cgroup+0x2f/0x3c0 [bfq]
 bfq_init_rq+0x1e8/0xb10 [bfq]
 bfq_insert_request.isra.0+0xa3/0x420 [bfq]
 bfq_insert_requests+0xca/0xf0 [bfq]
 blk_mq_dispatch_rq_list+0x4c0/0xb00
 __blk_mq_sched_dispatch_requests+0x15e/0x200
 blk_mq_sched_dispatch_requests+0x8b/0xc0
 __blk_mq_run_hw_queue+0x3ff/0x500
 __blk_mq_delay_run_hw_queue+0x23a/0x300
 blk_mq_run_hw_queue+0x14e/0x350
 blk_mq_sched_insert_request+0x181/0x1f0
 blk_execute_rq+0xf4/0x300
 scsi_execute_cmd+0x23e/0x350
 sr_do_ioctl+0x173/0x3d0 [sr_mod]
 sr_packet+0x60/0x90 [sr_mod]
 cdrom_get_track_info.constprop.0+0x125/0x170 [cdrom]
 cdrom_get_last_written+0x1d4/0x2d0 [cdrom]
 mmc_ioctl_cdrom_last_written+0x85/0x120 [cdrom]
 mmc_ioctl+0x10b/0x1d0 [cdrom]
 cdrom_ioctl+0xa66/0x1270 [cdrom]
 sr_block_ioctl+0xee/0x130 [sr_mod]
 blkdev_ioctl+0x1bb/0x3f0
 __x64_sys_ioctl+0xc7/0xe0
 do_syscall_64+0x34/0x80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Bart.