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BUG: KCSAN: data-race in bio_chain / bio_endio

read to 0xffff888129d890d4 of 2 bytes by interrupt on cpu 1:
 bio_remaining_done block/bio.c:1760 [inline]
 bio_endio+0x3e/0x400 block/bio.c:1790
 req_bio_endio block/blk-core.c:245 [inline]
 blk_update_request+0x427/0x7b0 block/blk-core.c:1464
 scsi_end_request+0x6b/0x360 drivers/scsi/scsi_lib.c:576
 scsi_io_completion+0x11d/0xc80 drivers/scsi/scsi_lib.c:960
 scsi_finish_command+0x283/0x380 drivers/scsi/scsi.c:228
 scsi_softirq_done+0x259/0x280 drivers/scsi/scsi_lib.c:1476
 blk_done_softirq+0x1eb/0x250 block/blk-softirq.c:37
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 do_IRQ+0x81/0x130 arch/x86/kernel/irq.c:263
 ret_from_intr+0x0/0x21
 find_watchpoint kernel/kcsan/core.c:105 [inline]
 check_access kernel/kcsan/core.c:446 [inline]
 __tsan_unaligned_write4+0x5f/0x110 kernel/kcsan/core.c:588
 vsnprintf+0xa03/0xb40 lib/vsprintf.c:2637
 snprintf+0x6f/0xa0 lib/vsprintf.c:2707
 proc_flush_task_mnt fs/proc/base.c:3143 [inline]
 proc_flush_task+0x10e/0x2e0 fs/proc/base.c:3217
 release_task+0x83/0xc60 kernel/exit.c:202
 wait_task_zombie kernel/exit.c:1080 [inline]
 wait_consider_task+0x1b3f/0x1c60 kernel/exit.c:1307
 do_wait_thread kernel/exit.c:1370 [inline]
 do_wait+0x1c9/0x4c0 kernel/exit.c:1441
 kernel_wait4+0x156/0x240 kernel/exit.c:1613
 __do_sys_wait4+0xea/0x100 kernel/exit.c:1625
 __se_sys_wait4 kernel/exit.c:1621 [inline]
 __x64_sys_wait4+0x5e/0x80 kernel/exit.c:1621
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888129d890d4 of 2 bytes by task 26208 on cpu 0:
 bio_set_flag include/linux/bio.h:239 [inline]
 bio_inc_remaining include/linux/bio.h:689 [inline]
 bio_chain+0x86/0xb0 block/bio.c:336
 __blk_queue_split+0x757/0xc40 block/blk-merge.c:345
 blk_mq_make_request+0x104/0xf60 block/blk-mq.c:1920
 generic_make_request block/blk-core.c:1066 [inline]
 generic_make_request+0x196/0x700 block/blk-core.c:1008
 submit_bio+0x96/0x3c0 block/blk-core.c:1192
 iomap_dio_submit_bio.isra.0+0xfc/0x120 fs/iomap/direct-io.c:70
 iomap_dio_bio_actor+0x40a/0x960 fs/iomap/direct-io.c:306
 iomap_dio_actor+0x87/0x3a0 fs/iomap/direct-io.c:382
 iomap_apply+0x20d/0x6a0 fs/iomap/apply.c:80
 iomap_dio_rw+0x67e/0x9a0 fs/iomap/direct-io.c:498
 ext4_dio_write_iter fs/ext4/file.c:438 [inline]
 ext4_file_write_iter+0xc38/0xd40 fs/ext4/file.c:545
 call_write_iter include/linux/fs.h:1902 [inline]
 aio_write+0x1de/0x2d0 fs/aio.c:1583
 __io_submit_one fs/aio.c:1815 [inline]
 io_submit_one+0x61d/0xdb0 fs/aio.c:1862
 __do_sys_io_submit fs/aio.c:1921 [inline]
 __se_sys_io_submit fs/aio.c:1891 [inline]
 __x64_sys_io_submit+0x104/0x2a0 fs/aio.c:1891
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26208 Comm: syz-executor.5 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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