[moderation] [block?] KCSAN: data-race in __blk_mq_sched_dispatch_requests / blk_mq_dispatch_rq_list (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bee0e7762ad2 Merge tag 'for-linus-iommufd' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=149b9ef8e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac34c1f29a8029df
dashboard link: https://syzkaller.appspot.com/bug?extid=2fbef85b8c8a6cf5faad
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/233be5f65dd2/disk-bee0e776.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/94423738a289/vmlinux-bee0e776.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0b977463fa9a/bzImage-bee0e776.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2fbef8...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __blk_mq_sched_dispatch_requests / blk_mq_dispatch_rq_list

write to 0xffff8881001994f8 of 4 bytes by task 43 on cpu 1:
blk_mq_dispatch_rq_list+0xf4d/0x1090
__blk_mq_sched_dispatch_requests+0x1ce/0xd20 block/blk-mq-sched.c:301
blk_mq_sched_dispatch_requests+0x99/0x100 block/blk-mq-sched.c:333
blk_mq_run_work_fn+0x65/0xe0 block/blk-mq.c:2434
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

read to 0xffff8881001994f8 of 4 bytes by task 9417 on cpu 0:
__blk_mq_do_dispatch_sched block/blk-mq-sched.c:97 [inline]
blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline]
__blk_mq_sched_dispatch_requests+0x28b/0xd20 block/blk-mq-sched.c:309
blk_mq_sched_dispatch_requests+0x99/0x100 block/blk-mq-sched.c:333
blk_mq_run_hw_queue+0x2a4/0x4c0 block/blk-mq.c:2264
blk_mq_get_tag+0x479/0x590 block/blk-mq-tag.c:170
__blk_mq_alloc_requests+0x642/0x9e0 block/blk-mq.c:501
blk_mq_get_new_requests block/blk-mq.c:2884 [inline]
blk_mq_submit_bio+0x468/0xd90 block/blk-mq.c:2982
__submit_bio+0x11c/0x350 block/blk-core.c:607
__submit_bio_noacct_mq block/blk-core.c:686 [inline]
submit_bio_noacct_nocheck+0x4ad/0x5e0 block/blk-core.c:715
submit_bio_noacct+0x70c/0x8c0 block/blk-core.c:809
submit_bio+0xb7/0xc0 block/blk-core.c:842
ext4_io_submit fs/ext4/page-io.c:378 [inline]
io_submit_add_bh fs/ext4/page-io.c:419 [inline]
ext4_bio_write_folio+0x6c0/0x9a0 fs/ext4/page-io.c:563
mpage_submit_folio fs/ext4/inode.c:1875 [inline]
mpage_map_and_submit_buffers fs/ext4/inode.c:2121 [inline]
mpage_map_and_submit_extent fs/ext4/inode.c:2260 [inline]
ext4_do_writepages+0x139f/0x2100 fs/ext4/inode.c:2685
ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2774
do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
__filemap_fdatawrite_range mm/filemap.c:420 [inline]
__filemap_fdatawrite mm/filemap.c:426 [inline]
filemap_flush+0x95/0xc0 mm/filemap.c:453
ext4_alloc_da_blocks+0x50/0x130 fs/ext4/inode.c:3077
ext4_release_file+0x5f/0x1c0 fs/ext4/file.c:169
__fput+0x299/0x630 fs/file_table.c:394
____fput+0x15/0x20 fs/file_table.c:422
task_work_run+0x135/0x1a0 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x604/0x16d0 kernel/exit.c:871
do_group_exit+0x101/0x150 kernel/exit.c:1021
get_signal+0xf4e/0x10a0 kernel/signal.c:2904
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:309
exit_to_user_mode_loop+0x6f/0xe0 kernel/entry/common.c:168
exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
irqentry_exit_to_user_mode+0x9/0x20 kernel/entry/common.c:309
irqentry_exit+0x12/0x40 kernel/entry/common.c:412
exc_general_protection+0x339/0x4c0 arch/x86/kernel/traps.c:642
asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:564

value changed: 0x00000009 -> 0x00000007

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9417 Comm: syz-executor.4 Not tainted 6.7.0-rc4-syzkaller-00009-gbee0e7762ad2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================
syz-executor.4 (9417) used greatest stack depth: 9192 bytes left


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