syzbot

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BUG: KCSAN: data-race in __blk_mq_sched_dispatch_requests / blk_mq_run_hw_queue

write to 0xffff888101eba610 of 8 bytes by task 228 on cpu 1:
 INIT_LIST_HEAD include/linux/list.h:38 [inline]
 list_splice_init include/linux/list.h:485 [inline]
 __blk_mq_sched_dispatch_requests+0x137/0x270 block/blk-mq-sched.c:306
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:358
 __blk_mq_run_hw_queue+0xc1/0x140 block/blk-mq.c:1785
 __blk_mq_delay_run_hw_queue+0x199/0x360 block/blk-mq.c:1862
 blk_mq_run_hw_queue+0x231/0x260 block/blk-mq.c:1915
 blk_mq_run_hw_queues+0x1d1/0x230 block/blk-mq.c:1978
 blk_mq_requeue_work+0x3b4/0x3e0 block/blk-mq.c:1121
 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

read to 0xffff888101eba610 of 8 bytes by task 20184 on cpu 0:
 list_empty_careful include/linux/list.h:321 [inline]
 blk_mq_hctx_has_pending block/blk-mq.c:99 [inline]
 blk_mq_run_hw_queue+0x12e/0x260 block/blk-mq.c:1911
 blk_mq_sched_insert_requests+0x130/0x200 block/blk-mq-sched.c:511
 blk_mq_flush_plug_list+0x372/0x460 block/blk-mq.c:2292
 blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1593
 blk_finish_plug+0x44/0x60 block/blk-core.c:1617
 read_pages+0x34b/0x5f0 mm/readahead.c:149
 page_cache_ra_unbounded+0x3d2/0x430 mm/readahead.c:238
 ondemand_readahead+0x4f8/0x700
 page_cache_sync_ra+0xaf/0xe0 mm/readahead.c:579
 page_cache_sync_readahead include/linux/pagemap.h:1029 [inline]
 filemap_get_pages mm/filemap.c:2556 [inline]
 filemap_read+0x3eb/0x16d0 mm/filemap.c:2642
 generic_file_read_iter+0x72/0x2a0 mm/filemap.c:2792
 ext4_file_read_iter+0x1db/0x290
 call_read_iter include/linux/fs.h:2156 [inline]
 generic_file_splice_read+0x24f/0x330 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888101cc4448 -> 0xffff888101eba608

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 20184 Comm: syz-executor.2 Not tainted 5.16.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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