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BUG: KCSAN: data-race in blk_stat_add / blk_stat_timer_fn

read to 0xffffe8ffffd2e248 of 4 bytes by interrupt on cpu 0:
 blk_rq_stat_sum block/blk-stat.c:31 [inline]
 blk_stat_timer_fn+0x364/0x3d0 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
 __tsan_read8+0x0/0x100 kernel/kcsan/core.c:588
 __getblk_gfp+0x50/0x570 fs/buffer.c:1358
 sb_getblk include/linux/buffer_head.h:325 [inline]
 __ext4_get_inode_loc+0x228/0x960 fs/ext4/inode.c:4240
 ext4_get_inode_loc+0x3f/0x50 fs/ext4/inode.c:4355
 ext4_reserve_inode_write+0x7f/0x150 fs/ext4/inode.c:5566
 ext4_mark_inode_dirty+0x7f/0x420 fs/ext4/inode.c:5732
 add_dirent_to_buf+0x263/0x390 fs/ext4/namei.c:2024
 ext4_add_entry+0x37b/0x8f0 fs/ext4/namei.c:2225
 ext4_add_nondir+0x61/0x190 fs/ext4/namei.c:2561
 ext4_create+0x177/0x300 fs/ext4/namei.c:2606
 lookup_open fs/namei.c:3241 [inline]
 do_last fs/namei.c:3331 [inline]
 path_openat+0x2b10/0x3580 fs/namei.c:3537
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 ksys_open include/linux/syscalls.h:1385 [inline]
 __do_sys_creat fs/open.c:1155 [inline]
 __se_sys_creat fs/open.c:1153 [inline]
 __x64_sys_creat+0x45/0x60 fs/open.c:1153
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffffe8ffffd2e248 of 4 bytes by interrupt on cpu 1:
 blk_rq_stat_add block/blk-stat.c:48 [inline]
 blk_stat_add+0x217/0x2c0 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29730 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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