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BUG: KCSAN: data-race in blk_mq_run_hw_queue / blk_mq_sched_insert_request

write to 0xffff888129c78810 of 8 bytes by task 2517 on cpu 0:
 __list_add include/linux/list.h:70 [inline]
 list_add include/linux/list.h:86 [inline]
 blk_mq_sched_bypass_insert block/blk-mq-sched.c:367 [inline]
 blk_mq_sched_insert_request+0x2f2/0x3e0 block/blk-mq-sched.c:394
 blk_mq_requeue_work+0x347/0x440 block/blk-mq.c:746
 process_one_work+0x424/0x930 kernel/workqueue.c:2264
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2410
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff888129c78810 of 8 bytes by interrupt on cpu 1:
 list_empty_careful include/linux/list.h:301 [inline]
 blk_mq_hctx_has_pending block/blk-mq.c:69 [inline]
 blk_mq_run_hw_queue+0x10a/0x1b0 block/blk-mq.c:1508
 blk_mq_run_hw_queues+0xa2/0xe0 block/blk-mq.c:1530
 scsi_end_request+0x338/0x350 drivers/scsi/scsi_lib.c:616
 scsi_io_completion+0x11e/0xcc0 drivers/scsi/scsi_lib.c:960
 scsi_finish_command+0x283/0x390 drivers/scsi/scsi.c:228
 scsi_softirq_done+0x249/0x270 drivers/scsi/scsi_lib.c:1476
 blk_done_softirq+0x1e6/0x250 block/blk-softirq.c:37
 __do_softirq+0x118/0x34a kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xb5/0xd0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 do_IRQ+0x7b/0x120 arch/x86/kernel/irq.c:263
 ret_from_intr+0x0/0x21
 inet_twsk_purge+0x30b/0x3a0 net/ipv4/inet_timewait_sock.c:264
 dccp_v4_exit_batch+0x1f/0x30 net/dccp/ipv4.c:1030
 ops_exit_list.isra.0+0x9e/0xb0 net/core/net_namespace.c:175
 cleanup_net+0x40a/0x6a0 net/core/net_namespace.c:589
 process_one_work+0x424/0x930 kernel/workqueue.c:2264
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2410
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 43 Comm: kworker/u4:2 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
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