[moderation] [block?] KCSAN: data-race in bt_for_each / flush_end_io (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 34afb82a3c67 Merge tag '6.10-rc6-smb3-server-fixes' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=108dac41980000
kernel config: https://syzkaller.appspot.com/x/.config?x=ba564f4ba39eebaa
dashboard link: https://syzkaller.appspot.com/bug?extid=477ba4d93a3c17287e14
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3f76f6140944/disk-34afb82a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/49cedff4d47b/vmlinux-34afb82a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aff987fd3a1d/bzImage-34afb82a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+477ba4...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in bt_for_each / flush_end_io

write to 0xffff888100e4e420 of 4 bytes by interrupt on cpu 0:
flush_end_io+0x444/0x780 block/blk-flush.c:249
__blk_mq_end_request+0x308/0x390 block/blk-mq.c:1047
blk_mq_end_request+0x3b/0x50 block/blk-mq.c:1059
lo_complete_rq+0xce/0x180 drivers/block/loop.c:389
blk_complete_reqs block/blk-mq.c:1132 [inline]
blk_done_softirq+0x74/0xb0 block/blk-mq.c:1137
handle_softirqs+0xc3/0x280 kernel/softirq.c:554
run_ksoftirqd+0x1c/0x30 kernel/softirq.c:928
smpboot_thread_fn+0x31c/0x4c0 kernel/smpboot.c:164
kthread+0x1d1/0x210 kernel/kthread.c:389
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff888100e4e420 of 4 bytes by task 25 on cpu 1:
blk_mq_find_and_get_req block/blk-mq-tag.c:260 [inline]
bt_iter block/blk-mq-tag.c:287 [inline]
__sbitmap_for_each_set include/linux/sbitmap.h:281 [inline]
sbitmap_for_each_set include/linux/sbitmap.h:302 [inline]
bt_for_each+0x291/0x480 block/blk-mq-tag.c:324
blk_mq_queue_tag_busy_iter+0x1a4/0x330 block/blk-mq-tag.c:533
blk_mq_timeout_work+0xc4/0x350 block/blk-mq.c:1644
process_one_work kernel/workqueue.c:3248 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3329
worker_thread+0x526/0x720 kernel/workqueue.c:3409
kthread+0x1d1/0x210 kernel/kthread.c:389
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000062 -> 0xffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25 Comm: kworker/1:0H Not tainted 6.10.0-rc7-syzkaller-00012-g34afb82a3c67 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: kblockd blk_mq_timeout_work
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup