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BUG: KCSAN: data-race in blk_stat_add / blk_stat_timer_fn

write to 0xffffe8ffffd359a0 of 8 bytes by interrupt on cpu 0:
 blk_rq_stat_init block/blk-stat.c:23 [inline]
 blk_stat_timer_fn+0x313/0x410 block/blk-stat.c:95
 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1417
 expire_timers+0x116/0x260 kernel/time/timer.c:1462
 __run_timers+0x338/0x3d0 kernel/time/timer.c:1731
 run_timer_softirq+0x19/0x30 kernel/time/timer.c:1744
 __do_softirq+0x13c/0x2c3 kernel/softirq.c:343
 asm_call_irq_on_stack+0xf/0x20
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x32/0x40 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:226 [inline]
 __irq_exit_rcu+0xb4/0xc0 kernel/softirq.c:420
 sysvec_apic_timer_interrupt+0x74/0x90 arch/x86/kernel/apic/apic.c:1096
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628

read to 0xffffe8ffffd359a0 of 8 bytes by interrupt on cpu 1:
 blk_rq_stat_add block/blk-stat.c:45 [inline]
 blk_stat_add+0x10c/0x230 block/blk-stat.c:74
 __blk_mq_end_request+0x142/0x230 block/blk-mq.c:546
 scsi_end_request+0x2a6/0x470 drivers/scsi/scsi_lib.c:604
 scsi_io_completion+0x104/0xfb0 drivers/scsi/scsi_lib.c:969
 scsi_finish_command+0x263/0x2b0 drivers/scsi/scsi.c:214
 scsi_softirq_done+0xdf/0x440 drivers/scsi/scsi_lib.c:1449
 blk_done_softirq+0x145/0x190 block/blk-mq.c:588
 __do_softirq+0x13c/0x2c3 kernel/softirq.c:343
 asm_call_irq_on_stack+0xf/0x20
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x32/0x40 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:226 [inline]
 __irq_exit_rcu+0xb4/0xc0 kernel/softirq.c:420
 common_interrupt+0xb5/0x130 arch/x86/kernel/irq.c:239
 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:619
 check_access kernel/kcsan/core.c:633 [inline]
 __tsan_unaligned_write4+0x15f/0x190 kernel/kcsan/core.c:841
 ext4_do_update_inode fs/ext4/inode.c:5081 [inline]
 ext4_mark_iloc_dirty+0x7a6/0x16e0 fs/ext4/inode.c:5725
 __ext4_mark_inode_dirty+0x4cd/0x5d0 fs/ext4/inode.c:5919
 ext4_dirty_inode+0xa6/0xc0 fs/ext4/inode.c:5955
 __mark_inode_dirty+0x72/0x6b0 fs/fs-writeback.c:2260
 mark_inode_dirty include/linux/fs.h:2181 [inline]
 generic_write_end+0x15e/0x250 fs/buffer.c:2202
 ext4_da_write_end+0x59b/0x760 fs/ext4/inode.c:3111
 generic_perform_write+0x23e/0x3a0 mm/filemap.c:3419
 ext4_buffered_write_iter+0x2e5/0x3d0 fs/ext4/file.c:270
 ext4_file_write_iter+0x45e/0x1090 fs/ext4/file.c:503
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4b0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x42a/0x780 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:933
 splice_direct_to_actor+0x345/0x650 fs/splice.c:888
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5db/0xca0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 30860 Comm: syz-executor.3 Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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