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BUG: KCSAN: data-race in blk_mq_dispatch_rq_list / blk_mq_do_dispatch_sched

write to 0xffff888100d34cf8 of 4 bytes by task 707 on cpu 0:
 blk_mq_update_dispatch_busy block/blk-mq.c:1237 [inline]
 blk_mq_dispatch_rq_list+0xefb/0x1040 block/blk-mq.c:1473
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:201 [inline]
 blk_mq_do_dispatch_sched+0x3b5/0x640 block/blk-mq-sched.c:214
 __blk_mq_sched_dispatch_requests+0x1eb/0x290 block/blk-mq-sched.c:329
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:360
 __blk_mq_run_hw_queue+0xbc/0x140 block/blk-mq.c:1500
 blk_mq_run_work_fn+0x3d/0x50 block/blk-mq.c:1832
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

read to 0xffff888100d34cf8 of 4 bytes by task 6501 on cpu 1:
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:128 [inline]
 blk_mq_do_dispatch_sched+0x9c/0x640 block/blk-mq-sched.c:214
 __blk_mq_sched_dispatch_requests+0x1eb/0x290 block/blk-mq-sched.c:329
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:360
 __blk_mq_run_hw_queue+0xbc/0x140 block/blk-mq.c:1500
 __blk_mq_delay_run_hw_queue+0x163/0x2f0 block/blk-mq.c:1577
 blk_mq_run_hw_queue+0x22c/0x250 block/blk-mq.c:1630
 blk_mq_get_tag+0x205/0x610 block/blk-mq-tag.c:127
 __blk_mq_alloc_request+0x22a/0x290 block/blk-mq.c:386
 blk_mq_submit_bio+0x26d/0xe80 block/blk-mq.c:2207
 __submit_bio_noacct_mq block/blk-core.c:1013 [inline]
 submit_bio_noacct+0x6f2/0x7e0 block/blk-core.c:1046
 submit_bio+0x10c/0x190 include/linux/vmstat.h:81
 submit_bh_wbc+0x2f3/0x330 fs/buffer.c:3050
 __block_write_full_page+0x648/0xa10 fs/buffer.c:1805
 block_write_full_page+0x240/0x260 fs/buffer.c:2976
 blkdev_writepage+0x20/0x30 fs/block_dev.c:639
 __writepage+0x32/0xc0 mm/page-writeback.c:2314
 write_cache_pages+0x4d7/0x810 mm/page-writeback.c:2249
 generic_writepages+0x64/0xa0 mm/page-writeback.c:2340
 blkdev_writepages+0x19/0x20 fs/block_dev.c:1679
 do_writepages+0x7b/0x150 mm/page-writeback.c:2355
 __filemap_fdatawrite_range mm/filemap.c:413 [inline]
 filemap_write_and_wait_range+0x20a/0x390 mm/filemap.c:686
 __generic_file_write_iter+0x231/0x300 mm/filemap.c:3775
 blkdev_write_iter+0x1ea/0x2b0 fs/block_dev.c:1643
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x69d/0x770 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000007 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6501 Comm: syz-executor.0 Tainted: G        W         5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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