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BUG: KCSAN: data-race in blk_stat_add / blk_stat_timer_fn

write to 0xffffe8ffffc24400 of 8 bytes by interrupt on cpu 1:
 blk_rq_stat_init block/blk-stat.c:25 [inline]
 blk_stat_timer_fn+0x30d/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
 arch_local_irq_enable arch/x86/include/asm/paravirt.h:762 [inline]
 preempt_schedule_irq+0x4d/0x90 kernel/sched/core.c:4337
 restore_regs_and_return_to_kernel+0x0/0x25
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
 kcsan_setup_watchpoint+0x1d4/0x460 kernel/kcsan/core.c:429
 check_access kernel/kcsan/core.c:459 [inline]
 __tsan_read1+0xc2/0x100 kernel/kcsan/core.c:586
 __fat_get_block fs/fat/inode.c:136 [inline]
 fat_get_block+0xfb/0x4e0 fs/fat/inode.c:189
 __block_write_begin_int+0x2ea/0xf10 fs/buffer.c:2008
 __block_write_begin fs/buffer.c:2058 [inline]
 block_write_begin+0x77/0x160 fs/buffer.c:2117
 cont_write_begin+0x3d6/0x670 fs/buffer.c:2466
 fat_write_begin+0x72/0xc0 fs/fat/inode.c:235
 generic_perform_write+0x136/0x320 mm/filemap.c:3309
 __generic_file_write_iter+0x251/0x380 mm/filemap.c:3438
 generic_file_write_iter+0x28c/0x38c mm/filemap.c:3470
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write+0x388/0x4a0 fs/read_write.c:483
 __vfs_write+0xb1/0xc0 fs/read_write.c:496
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffe8ffffc24400 of 8 bytes by interrupt on cpu 0:
 blk_rq_stat_add block/blk-stat.c:47 [inline]
 blk_stat_add+0x1dc/0x2c0 block/blk-stat.c:74
 __blk_mq_end_request block/blk-mq.c:527 [inline]
 blk_mq_end_request+0x256/0x2b0 block/blk-mq.c:548
 lo_complete_rq+0x136/0x1a0 drivers/block/loop.c:487
 blk_done_softirq+0x1eb/0x250 block/blk-softirq.c:37
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
 smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9 Comm: ksoftirqd/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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