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BUG: KCSAN: data-race in __blk_mq_sched_dispatch_requests / blk_mq_dispatch_rq_list

read-write to 0xffff888100a22cf8 of 4 bytes by task 19208 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_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_get_tag+0x21b/0x640 block/blk-mq-tag.c:175
 __blk_mq_alloc_requests+0x883/0xe10 block/blk-mq.c:576
 blk_mq_get_new_requests block/blk-mq.c:3040 [inline]
 blk_mq_submit_bio+0xa3d/0x1120 block/blk-mq.c:3170
 __submit_bio+0x54/0x3d0 block/blk-core.c:673
 __submit_bio_noacct_mq block/blk-core.c:756 [inline]
 submit_bio_noacct_nocheck+0x153/0x620 block/blk-core.c:790
 submit_bio_noacct+0x760/0x980 block/blk-core.c:925
 submit_bio+0x2a4/0x2c0 block/blk-core.c:966
 blk_crypto_submit_bio include/linux/blk-crypto.h:212 [inline]
 ext4_io_submit fs/ext4/page-io.c:396 [inline]
 io_submit_add_bh fs/ext4/page-io.c:452 [inline]
 ext4_bio_write_folio+0x702/0xa10 fs/ext4/page-io.c:547
 mpage_submit_folio fs/ext4/inode.c:2094 [inline]
 mpage_process_page_bufs+0x484/0x5e0 fs/ext4/inode.c:2201
 mpage_prepare_extent_to_map+0x83e/0xca0 fs/ext4/inode.c:2743
 ext4_do_writepages+0x70f/0x2870 fs/ext4/inode.c:2884
 ext4_writepages+0x191/0x300 fs/ext4/inode.c:3032
 do_writepages+0x1b9/0x300 mm/page-writeback.c:2560
 __writeback_single_inode+0x7b/0x790 fs/fs-writeback.c:1788
 writeback_sb_inodes+0x4d9/0xaa0 fs/fs-writeback.c:2099
 __writeback_inodes_wb+0x8a/0x180 fs/fs-writeback.c:2175
 wb_writeback+0x21e/0x510 fs/fs-writeback.c:2286
 wb_check_old_data_flush fs/fs-writeback.c:2390 [inline]
 wb_do_writeback fs/fs-writeback.c:2469 [inline]
 wb_workfn+0x740/0xa50 fs/fs-writeback.c:2497
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 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 to 0xffff888100a22cf8 of 4 bytes by task 2946 on cpu 0:
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:95 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0x295/0xce0 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:2532
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 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

value changed: 0x00000007 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2946 Comm: kworker/0:1H Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: kblockd blk_mq_run_work_fn
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