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BUG: KCSAN: data-race in blk_stat_add / blk_stat_timer_fn

write to 0xffffe8ffffd2e3a0 of 4 bytes by interrupt on cpu 0:
 blk_rq_stat_init block/blk-stat.c:24 [inline]
 blk_stat_timer_fn+0x2ed/0x3d0 block/blk-stat.c:95
 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
 is_atomic kernel/kcsan/core.c:174 [inline]
 should_watch kernel/kcsan/core.c:203 [inline]
 check_access kernel/kcsan/core.c:458 [inline]
 __tsan_read8+0x8e/0x100 kernel/kcsan/core.c:589
 compound_head include/linux/page-flags.h:174 [inline]
 PageReclaim include/linux/page-flags.h:364 [inline]
 set_page_dirty+0xc0/0x2b0 mm/page-writeback.c:2566
 block_page_mkwrite+0x1d8/0x230 fs/buffer.c:2526
 ext4_page_mkwrite+0x5ca/0xe50 fs/ext4/inode.c:5902
 do_page_mkwrite+0x100/0x210 mm/memory.c:2276
 do_shared_fault mm/memory.c:3650 [inline]
 do_fault mm/memory.c:3718 [inline]
 handle_pte_fault mm/memory.c:3945 [inline]
 __handle_mm_fault+0x1e45/0x2e00 mm/memory.c:4075
 handle_mm_fault+0x21b/0x530 mm/memory.c:4112
 do_user_addr_fault arch/x86/mm/fault.c:1441 [inline]
 __do_page_fault+0x456/0x8d0 arch/x86/mm/fault.c:1506
 do_page_fault+0x38/0x194 arch/x86/mm/fault.c:1530
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1203

read to 0xffffe8ffffd2e3a0 of 4 bytes by interrupt on cpu 1:
 blk_rq_stat_add block/blk-stat.c:48 [inline]
 blk_stat_add+0x205/0x2c0 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
 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:690
 default_idle_call+0x1e/0x40 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x1c2/0x290 kernel/sched/idle.c:269
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
 start_secondary+0x168/0x1b0 arch/x86/kernel/smpboot.c:264
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 0 Comm: swapper/1 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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