On 4/10/23 11:47, Bart Van Assche wrote:
On 4/9/23 18:57, Yu Kuai wrote:
Hi, Bart
在 2023/04/08 2:41, Bart Van Assche 写道:
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
I found this call trace quite weird, I can't figure out how
bfq_insert_requests can be called from blk_mq_dispatch_rq_list,
can you show the add2line result?
Hi Kuai,
Thanks for having taken a look. I ran my tests with this patch series on
top of Jens' for-next branch: "[PATCH v2 00/12] Submit zoned writes in
order"
(https://lore.kernel.org/linux-block/20230407235822.1672286-1-bvanassche@xxxxxxx/T/#m4c8c7ca5a5627510dc1709847b11589e8791b6b6). I will take a closer look and see which of these two patch series needs to be adjusted.
(replying to my own e-mail)
I think I found the root cause: bio->bi_bdev is NULL for pass-through
requests and BFQ doesn't like it that bio->bi_bdev is NULL. I will make
sure that pass-through requests are not submitted to any I/O scheduler.
Thanks,
Bart.
