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BUG: KCSAN: data-race in blk_mq_dispatch_rq_list / blk_mq_dispatch_rq_list

read-write to 0xffff88810038caf8 of 4 bytes by task 2942 on cpu 1:
 blk_mq_update_dispatch_busy block/blk-mq.c:1996 [inline]
 blk_mq_dispatch_rq_list+0xc3e/0xef0 block/blk-mq.c:2205
 __blk_mq_sched_dispatch_requests+0x1db/0xce0 block/blk-mq-sched.c:299
 blk_mq_sched_dispatch_requests+0x86/0x120 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x17d/0x220 block/blk-mq.c:2356
 blk_mq_run_hw_queues+0x18e/0x270 block/blk-mq.c:2404
 blk_mq_requeue_work+0x3ca/0x400 block/blk-mq.c:1571
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3470
 worker_thread+0x569/0x750 kernel/workqueue.c:3551
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read-write to 0xffff88810038caf8 of 4 bytes by task 5914 on cpu 0:
 blk_mq_update_dispatch_busy block/blk-mq.c:1996 [inline]
 blk_mq_dispatch_rq_list+0xc3e/0xef0 block/blk-mq.c:2205
 __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+0x86c/0xce0 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0x86/0x120 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x17d/0x220 block/blk-mq.c:2356
 blk_mq_dispatch_list+0x83d/0x9f0 arch/x86/include/asm/bitops.h:-1
 blk_mq_flush_plug_list+0x2cd/0x320 block/blk-mq.c:2966
 blk_add_rq_to_plug+0xe4/0x360 block/blk-mq.c:1386
 blk_mq_submit_bio+0xc01/0x1120 block/blk-mq.c:3198
 __submit_bio+0x54/0x3d0 block/blk-core.c:673
 __submit_bio_noacct_mq block/blk-core.c:756 [inline]
 submit_bio_noacct_nocheck+0x1c6/0x620 block/blk-core.c:790
 submit_bio_noacct+0x760/0x980 block/blk-core.c:925
 submit_bio+0x2a4/0x2c0 block/blk-core.c:966
 bio_chain_and_submit+0x84/0xb0 block/bio.c:376
 __blkdev_issue_zero_pages+0x1f7/0x240 block/blk-lib.c:215
 blkdev_issue_zero_pages block/blk-lib.c:231 [inline]
 blkdev_issue_zeroout+0x3a1/0x4f0 block/blk-lib.c:312
 blkdev_fallocate+0x36d/0x3a0 block/fops.c:911
 vfs_fallocate+0x3ac/0x400 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0x7a/0xd0 fs/open.c:365
 x64_sys_call+0x1e1d/0x2550 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000007 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5914 Comm: syz.4.843 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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