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BUG: KCSAN: data-race in blk_stat_add / blk_stat_timer_fn

read to 0xffffe8ffffd2e328 of 8 bytes by interrupt on cpu 0:
 blk_rq_stat_sum block/blk-stat.c:35 [inline]
 blk_rq_stat_sum block/blk-stat.c:29 [inline]
 blk_stat_timer_fn+0x222/0x3d0 block/blk-stat.c:94
 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers kernel/time/timer.c:1773 [inline]
 __run_timers kernel/time/timer.c:1740 [inline]
 run_timer_softirq+0xc0c/0xcd0 kernel/time/timer.c:1786
 __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]
 smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 __sanitizer_cov_trace_switch+0x49/0x80 kernel/kcov.c:310
 __read_once_size+0x25/0xe0 include/linux/compiler.h:232
 arch_atomic_read arch/x86/include/asm/atomic.h:31 [inline]
 atomic_read include/asm-generic/atomic-instrumented.h:41 [inline]
 __fget_light+0x5f/0x190 fs/file.c:770
 __fdget+0x24/0x40 fs/file.c:784
 fdget include/linux/file.h:62 [inline]
 do_epoll_wait+0xbb/0x180 fs/eventpoll.c:2254
 __do_sys_epoll_wait fs/eventpoll.c:2283 [inline]
 __se_sys_epoll_wait fs/eventpoll.c:2280 [inline]
 __x64_sys_epoll_wait+0x5e/0x80 fs/eventpoll.c:2280
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffffe8ffffd2e328 of 8 bytes by interrupt on cpu 1:
 blk_rq_stat_add block/blk-stat.c:46 [inline]
 blk_stat_add+0x1c7/0x2c0 block/blk-stat.c:74
 __blk_mq_end_request+0x22d/0x270 block/blk-mq.c:527
 scsi_end_request+0x1dd/0x360 drivers/scsi/scsi_lib.c:610
 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
 __sanitizer_cov_trace_pc+0x2b/0x50 kernel/kcov.c:187
 mark_nosave_pages kernel/power/snapshot.c:1058 [inline]
 create_basic_memory_bitmaps.cold+0x95/0x158 kernel/power/snapshot.c:1107
 snapshot_open+0x378/0x3e0 kernel/power/user.c:88
 misc_open+0x26a/0x2d0 drivers/char/misc.c:141
 chrdev_open+0x150/0x380 fs/char_dev.c:414
 do_dentry_open+0x301/0x970 fs/open.c:797
 vfs_open+0x62/0x80 fs/open.c:914
 do_last fs/namei.c:3420 [inline]
 path_openat+0xf9f/0x3580 fs/namei.c:3537
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_openat fs/open.c:1124 [inline]
 __se_sys_openat fs/open.c:1118 [inline]
 __x64_sys_openat+0x62/0x80 fs/open.c:1118
 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: 1 PID: 4584 Comm: syz-executor.0 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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