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BUG: KCSAN: data-race in blk_mq_request_bypass_insert / blk_mq_run_hw_queue

write to 0xffff888101f27810 of 8 bytes by task 226 on cpu 1:
 __list_add include/linux/list.h:72 [inline]
 list_add include/linux/list.h:88 [inline]
 blk_mq_request_bypass_insert+0x6a/0x130 block/blk-mq.c:2164
 blk_mq_sched_insert_request+0xfd/0x220 block/blk-mq-sched.c:460
 blk_mq_requeue_work+0x217/0x3e0 block/blk-mq.c:1112
 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

read to 0xffff888101f27810 of 8 bytes by task 14799 on cpu 0:
 list_empty_careful include/linux/list.h:321 [inline]
 blk_mq_hctx_has_pending block/blk-mq.c:99 [inline]
 blk_mq_run_hw_queue+0x12e/0x260 block/blk-mq.c:1911
 blk_mq_sched_insert_requests+0x130/0x200 block/blk-mq-sched.c:511
 blk_mq_flush_plug_list+0x372/0x460 block/blk-mq.c:2292
 blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1593
 blk_finish_plug+0x44/0x60 block/blk-core.c:1617
 ext4_writepages+0x1981/0x1e80 fs/ext4/inode.c:2846
 do_writepages+0x1cb/0x330 mm/page-writeback.c:2364
 filemap_fdatawrite_wbc mm/filemap.c:407 [inline]
 __filemap_fdatawrite_range mm/filemap.c:440 [inline]
 file_write_and_wait_range+0x132/0x1d0 mm/filemap.c:824
 ext4_sync_file+0x105/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:182
 generic_write_sync include/linux/fs.h:2955 [inline]
 ext4_buffered_write_iter+0x322/0x380 fs/ext4/file.c:277
 ext4_file_write_iter+0x2e7/0x1200
 __kernel_write+0x32e/0x5e0 fs/read_write.c:535
 do_acct_process+0xb4d/0xd40 kernel/acct.c:518
 slow_acct_process kernel/acct.c:577 [inline]
 acct_process+0x1ad/0x250 kernel/acct.c:601
 do_exit+0x612/0x17a0 kernel/exit.c:822
 do_group_exit+0xce/0x180 kernel/exit.c:929
 get_signal+0xfc3/0x1550 kernel/signal.c:2852
 arch_do_signal_or_restart+0x8c/0x2e0 arch/x86/kernel/signal.c:868
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x113/0x190 kernel/entry/common.c:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:300
 do_syscall_64+0x50/0xd0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888101f27808 -> 0xffff8881029f49c8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14799 Comm: syz-executor.2 Tainted: G        W         5.16.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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