[moderation] [block?] KCSAN: data-race in __mod_timer / blk_add_timer (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9b6de136b5f0 Merge tag 'loongarch-fixes-6.7-1' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17b69768e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c1151391aefc0c3
dashboard link: https://syzkaller.appspot.com/bug?extid=a987d71b88b187bf148b
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/66e487a84769/disk-9b6de136.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/68701b15ec8c/vmlinux-9b6de136.xz
kernel image: https://storage.googleapis.com/syzbot-assets/78c7cba56794/bzImage-9b6de136.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a987d7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __mod_timer / blk_add_timer

write to 0xffff888100c5cb98 of 8 bytes by task 77 on cpu 1:
__mod_timer+0x5fd/0x860 kernel/time/timer.c:1121
mod_timer+0x1f/0x30 kernel/time/timer.c:1190
blk_mq_timeout_work+0x185/0x350 block/blk-mq.c:1661
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 0xffff888100c5cb98 of 8 bytes by task 20857 on cpu 0:
blk_add_timer+0x118/0x190
blk_mq_start_request+0x10e/0x2d0 block/blk-mq.c:1260
loop_queue_rq+0x4c/0x650 drivers/block/loop.c:1851
__blk_mq_issue_directly block/blk-mq.c:2578 [inline]
blk_mq_request_issue_directly+0x1d6/0x330 block/blk-mq.c:2663
blk_mq_plug_issue_direct+0x156/0x520 block/blk-mq.c:2684
blk_mq_flush_plug_list+0x2b6/0xdc0 block/blk-mq.c:2793
blk_add_rq_to_plug+0x108/0x3e0 block/blk-mq.c:1294
blk_mq_submit_bio+0x61a/0xd90 block/blk-mq.c:2996
__submit_bio+0x11c/0x350 block/blk-core.c:599
__submit_bio_noacct_mq block/blk-core.c:678 [inline]
submit_bio_noacct_nocheck+0x449/0x5e0 block/blk-core.c:707
submit_bio_noacct+0x71c/0x8c0 block/blk-core.c:801
submit_bio+0xb7/0xc0 block/blk-core.c:834
submit_bh_wbc+0x2ca/0x300 fs/buffer.c:2821
__block_write_full_folio+0x580/0x8a0 fs/buffer.c:1906
block_write_full_page+0x2d3/0x390
blkdev_writepage+0x24/0x30 block/fops.c:415
writepage_cb+0x36/0xc0 mm/page-writeback.c:2537
write_cache_pages+0x38d/0x740 mm/page-writeback.c:2474
do_writepages+0x20f/0x340 mm/page-writeback.c:2558
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
__filemap_fdatawrite_range mm/filemap.c:420 [inline]
filemap_write_and_wait_range+0xe0/0x210 mm/filemap.c:675
direct_write_fallback+0x79/0x110 fs/libfs.c:1946
blkdev_write_iter+0x331/0x390 block/fops.c:693
do_iter_write+0x4ad/0x770 fs/read_write.c:860
vfs_writev+0x1a8/0x320 fs/read_write.c:933
do_pwritev fs/read_write.c:1030 [inline]
__do_sys_pwritev2 fs/read_write.c:1089 [inline]
__se_sys_pwritev2+0x10c/0x1d0 fs/read_write.c:1080
__x64_sys_pwritev2+0x78/0x90 fs/read_write.c:1080
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x000000010000e4f5 -> 0x000000010000ee50

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 20857 Comm: syz-executor.3 Not tainted 6.7.0-rc2-syzkaller-00029-g9b6de136b5f0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.