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BUG: KCSAN: data-race in blk_stat_add / blk_stat_timer_fn

read to 0xffffe8ffffd35c20 of 8 bytes by interrupt on cpu 0:
 blk_rq_stat_sum block/blk-stat.c:37 [inline]
 blk_stat_timer_fn+0x273/0x410 block/blk-stat.c:94
 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
 get_current arch/x86/include/asm/current.h:15 [inline]
 write_comp_data kernel/kcov.c:217 [inline]
 __sanitizer_cov_trace_cmp4+0xd/0xa0 kernel/kcov.c:258
 ext4_es_end fs/ext4/extents_status.c:202 [inline]
 __es_tree_search fs/ext4/extents_status.c:220 [inline]
 __es_remove_extent+0x153/0xec0 fs/ext4/extents_status.c:1321
 ext4_es_insert_delayed_block+0xb3/0x3b0 fs/ext4/extents_status.c:2008
 ext4_insert_delayed_block fs/ext4/inode.c:1681 [inline]
 ext4_da_map_blocks fs/ext4/inode.c:1771 [inline]
 ext4_da_get_block_prep+0x582/0x9a0 fs/ext4/inode.c:1835
 ext4_block_write_begin+0x414/0xc00 fs/ext4/inode.c:1077
 ext4_da_write_begin+0x50a/0xaf0 fs/ext4/inode.c:3016
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3408
 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

read-write to 0xffffe8ffffd35c20 of 8 bytes by interrupt on cpu 1:
 blk_rq_stat_add block/blk-stat.c:47 [inline]
 blk_stat_add+0x173/0x230 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
 native_restore_fl arch/x86/include/asm/irqflags.h:41 [inline]
 arch_local_irq_restore arch/x86/include/asm/irqflags.h:84 [inline]
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irqrestore+0x32/0x50 kernel/locking/spinlock.c:191
 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
 __test_set_page_writeback+0x3fa/0x4d0 mm/page-writeback.c:2803
 ext4_bio_write_page+0xfe/0xe70 fs/ext4/page-io.c:450
 mpage_submit_page fs/ext4/inode.c:2101 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2349 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2488 [inline]
 ext4_writepages+0xea2/0x1e50 fs/ext4/inode.c:2801
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
 __filemap_fdatawrite mm/filemap.c:430 [inline]
 filemap_flush+0x1f/0x30 mm/filemap.c:457
 ext4_alloc_da_blocks+0x4a/0x100 fs/ext4/inode.c:3165
 ext4_release_file+0x5b/0x1d0 fs/ext4/file.c:142
 __fput+0x24b/0x4e0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0x8e/0x110 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x16b/0x1a0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 28699 Comm: syz-executor.1 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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