syzbot

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BUG: KCSAN: data-race in blk_mq_dispatch_rq_list / blk_mq_dispatch_rq_list

read-write to 0xffff8881008abaf8 of 4 bytes by task 24 on cpu 1:
 blk_mq_update_dispatch_busy block/blk-mq.c:2016 [inline]
 blk_mq_dispatch_rq_list+0xc76/0xf80 block/blk-mq.c:2225
 __blk_mq_sched_dispatch_requests+0x1c8/0xc70 block/blk-mq-sched.c:299
 blk_mq_sched_dispatch_requests+0x86/0x120 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x17e/0x220 block/blk-mq.c:2375
 blk_mq_run_hw_queues+0x18e/0x270 block/blk-mq.c:2424
 blk_mq_requeue_work+0x3b9/0x3f0 block/blk-mq.c:1591
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffff8881008abaf8 of 4 bytes by task 48 on cpu 0:
 blk_mq_update_dispatch_busy block/blk-mq.c:2006 [inline]
 blk_mq_dispatch_rq_list+0x8d3/0xf80 block/blk-mq.c:2229
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0x7eb/0xc70 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0x86/0x120 block/blk-mq-sched.c:329
 blk_mq_run_work_fn+0x66/0xe0 block/blk-mq.c:2551
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x00000003 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 48 Comm: kworker/0:1H Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: kblockd blk_mq_run_work_fn
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