syzbot

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BUG: KCSAN: data-race in __blk_mq_sched_dispatch_requests / blk_mq_request_bypass_insert

write to 0xffff8881027c1c10 of 8 bytes by task 41 on cpu 1:
 __list_add include/linux/list.h:72 [inline]
 list_add include/linux/list.h:88 [inline]
 blk_mq_request_bypass_insert+0x6a/0x140 block/blk-mq.c:2359
 blk_mq_sched_insert_request+0xfd/0x220 block/blk-mq-sched.c:441
 blk_mq_requeue_work+0x39b/0x400 block/blk-mq.c:1312
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffff8881027c1c10 of 8 bytes by task 5593 on cpu 0:
 list_empty_careful include/linux/list.h:329 [inline]
 __blk_mq_sched_dispatch_requests+0x80/0x270 block/blk-mq-sched.c:284
 blk_mq_sched_dispatch_requests+0x8f/0xf0 block/blk-mq-sched.c:339
 __blk_mq_run_hw_queue+0x7e/0x100 block/blk-mq.c:1974
 __blk_mq_delay_run_hw_queue+0x194/0x390 block/blk-mq.c:2051
 blk_mq_run_hw_queue+0x180/0x310 block/blk-mq.c:2102
 blk_mq_sched_insert_requests+0x1cb/0x2a0 block/blk-mq-sched.c:493
 blk_mq_dispatch_plug_list+0x1e9/0x2c0 block/blk-mq.c:2597
 blk_mq_flush_plug_list+0x2ea/0x340 block/blk-mq.c:2639
 __blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1240
 blk_finish_plug+0x44/0x60 block/blk-core.c:1264
 __iomap_dio_rw+0xc50/0xf80 fs/iomap/direct-io.c:599
 iomap_dio_rw+0x38/0x80 fs/iomap/direct-io.c:681
 ext4_dio_read_iter fs/ext4/file.c:79 [inline]
 ext4_file_read_iter+0x19c/0x200 fs/ext4/file.c:130
 call_read_iter include/linux/fs.h:2044 [inline]
 generic_file_splice_read+0x1de/0x2c0 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2ac/0x660 fs/splice.c:870
 do_splice_direct+0xfb/0x180 fs/splice.c:979
 do_sendfile+0x3ad/0x900 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1297
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff8881027c1c08 -> 0xffff8881030f3448

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5593 Comm: syz-executor.2 Not tainted 5.18.0-rc7-syzkaller-00136-g3b5e1590a267-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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