KCSAN: data-race in blk_mq_request_bypass_insert / blk_mq_run_hw_queue (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c70672d8 Merge tag 's390-5.9-5' of git://git.kernel.org/pu..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12626771900000
kernel config: https://syzkaller.appspot.com/x/.config?x=8b13025dd241bdba
dashboard link: https://syzkaller.appspot.com/bug?extid=f5359a7d0291ed059d6a
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f5359a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in blk_mq_request_bypass_insert / blk_mq_run_hw_queue

write to 0xffff888129f94810 of 8 bytes by task 3256 on cpu 1:
__list_add include/linux/list.h:70 [inline]
list_add include/linux/list.h:86 [inline]
blk_mq_request_bypass_insert+0x6a/0x130 block/blk-mq.c:1859
blk_mq_sched_insert_request+0x1b4/0x330 block/blk-mq-sched.c:559
blk_mq_requeue_work+0x36b/0x490 block/blk-mq.c:813
process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
kthread+0x20d/0x230 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff888129f94810 of 8 bytes by task 32104 on cpu 0:
list_empty_careful include/linux/list.h:319 [inline]
blk_mq_hctx_has_pending block/blk-mq.c:72 [inline]
blk_mq_run_hw_queue+0x12e/0x260 block/blk-mq.c:1660
blk_mq_sched_insert_request+0x2ae/0x330 block/blk-mq-sched.c:576
blk_mq_submit_bio+0x988/0x1130 block/blk-mq.c:2224
__submit_bio_noacct_mq block/blk-core.c:1180 [inline]
submit_bio_noacct+0x772/0x950 block/blk-core.c:1213
submit_bio+0x200/0x370 block/blk-core.c:1283
submit_bh_wbc+0x397/0x3d0 fs/buffer.c:3070
submit_bh fs/buffer.c:3076 [inline]
__sync_dirty_buffer+0x12c/0x1d0 fs/buffer.c:3171
sync_dirty_buffer+0x16/0x20 fs/buffer.c:3184
ext4_write_inode+0x216/0x330 fs/ext4/inode.c:5165
write_inode+0x8e/0x250 fs/fs-writeback.c:1320
__writeback_single_inode+0x31a/0x600 fs/fs-writeback.c:1516
writeback_single_inode+0x11f/0x580 fs/fs-writeback.c:1570
sync_inode fs/fs-writeback.c:2605 [inline]
sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2625
ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
ext4_sync_file+0x335/0x6e0 fs/ext4/fsync.c:170
vfs_fsync_range+0x107/0x120 fs/sync.c:200
generic_write_sync include/linux/fs.h:2747 [inline]
ext4_buffered_write_iter+0x369/0x3b0 fs/ext4/file.c:276
ext4_file_write_iter+0x768/0x1060 include/linux/fs.h:784
call_write_iter include/linux/fs.h:1882 [inline]
do_iter_readv_writev+0x32e/0x3d0 fs/read_write.c:713
do_iter_write+0x112/0x4b0 fs/read_write.c:1018
vfs_iter_write+0x4c/0x70 fs/read_write.c:1059
iter_file_splice_write+0x41a/0x770 fs/splice.c:750
do_splice_from fs/splice.c:846 [inline]
direct_splice_actor+0x95/0x160 fs/splice.c:1016
splice_direct_to_actor+0x365/0x660 fs/splice.c:971
do_splice_direct+0xf2/0x170 fs/splice.c:1059
do_sendfile+0x56a/0xba0 fs/read_write.c:1540
__do_sys_sendfile64 fs/read_write.c:1595 [inline]
__se_sys_sendfile64 fs/read_write.c:1587 [inline]
__x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1587
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 32104 Comm: syz-executor.1 Not tainted 5.9.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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