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BUG: KCSAN: data-race in blk_stat_add / blk_stat_timer_fn

write to 0xffffe8ffffd2e4b0 of 8 bytes by interrupt on cpu 0:
 blk_rq_stat_init block/blk-stat.c:23 [inline]
 blk_stat_timer_fn+0x2ce/0x3d0 block/blk-stat.c:95
 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1405
 expire_timers kernel/time/timer.c:1450 [inline]
 __run_timers kernel/time/timer.c:1774 [inline]
 __run_timers kernel/time/timer.c:1741 [inline]
 run_timer_softirq+0xbe3/0xcb0 kernel/time/timer.c:1787
 __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:546 [inline]
 smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1146
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 __read_once_size include/linux/compiler.h:232 [inline]
 arch_atomic64_read arch/x86/include/asm/atomic64_64.h:22 [inline]
 atomic64_read include/asm-generic/atomic-instrumented.h:838 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
 find_watchpoint kernel/kcsan/core.c:117 [inline]
 check_access kernel/kcsan/core.c:537 [inline]
 __tsan_unaligned_write1+0x2f/0x80 kernel/kcsan/core.c:683
 mprotect_fixup+0x32a/0x510 mm/mprotect.c:441
 do_mprotect_pkey+0x3eb/0x660 mm/mprotect.c:553
 __do_sys_mprotect mm/mprotect.c:578 [inline]
 __se_sys_mprotect mm/mprotect.c:575 [inline]
 __x64_sys_mprotect+0x51/0x70 mm/mprotect.c:575
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffe8ffffd2e4b0 of 8 bytes by interrupt on cpu 1:
 blk_rq_stat_add block/blk-stat.c:45 [inline]
 blk_stat_add+0x18c/0x2c0 block/blk-stat.c:74
 __blk_mq_end_request+0x22f/0x2d0 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:546 [inline]
 do_IRQ+0x81/0x130 arch/x86/kernel/irq.c:263
 ret_from_intr+0x0/0x21
 __sanitizer_cov_trace_pc+0x0/0x50 kernel/kcov.c:915
 unmap_single_vma+0x144/0x200 mm/memory.c:1300
 unmap_vmas+0xda/0x1a0 mm/memory.c:1332
 exit_mmap+0x13e/0x300 mm/mmap.c:3130
 __mmput kernel/fork.c:1088 [inline]
 mmput+0xea/0x280 kernel/fork.c:1109
 exit_mm kernel/exit.c:485 [inline]
 do_exit+0x60d/0x18a0 kernel/exit.c:788
 do_group_exit+0xb4/0x1c0 kernel/exit.c:899
 get_signal+0x2a2/0x1320 kernel/signal.c:2734
 do_signal+0x2f/0x6c0 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 32064 Comm: syz-executor.3 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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