syzbot

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BUG: KCSAN: data-race in blk_mq_dispatch_rq_list / blk_mq_dispatch_rq_list

read to 0xffff88810219baf8 of 4 bytes by task 3522 on cpu 1:
 blk_mq_update_dispatch_busy block/blk-mq.c:1983 [inline]
 blk_mq_dispatch_rq_list+0xd7b/0xfa0 block/blk-mq.c:2204
 __blk_mq_sched_dispatch_requests+0x1ce/0xd50 block/blk-mq-sched.c:301
 blk_mq_sched_dispatch_requests+0x88/0x120 block/blk-mq-sched.c:331
 blk_mq_run_hw_queue+0x18a/0x230 block/blk-mq.c:2354
 blk_mq_run_hw_queues+0x1ac/0x240 block/blk-mq.c:2403
 blk_mq_requeue_work+0x3fa/0x430 block/blk-mq.c:1568
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 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

write to 0xffff88810219baf8 of 4 bytes by task 46 on cpu 0:
 blk_mq_dispatch_rq_list+0xd99/0xfa0
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:170 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline]
 __blk_mq_sched_dispatch_requests+0x604/0xd50 block/blk-mq-sched.c:309
 blk_mq_sched_dispatch_requests+0x88/0x120 block/blk-mq-sched.c:331
 blk_mq_run_work_fn+0x65/0xe0 block/blk-mq.c:2530
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 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: 0x00000002 -> 0x00000003

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 46 Comm: kworker/0:1H Not tainted 6.13.0-rc2-syzkaller-00031-gf92f4749861b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: kblockd blk_mq_run_work_fn
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