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BUG: KCSAN: data-race in __wb_update_bandwidth / percpu_counter_add_batch

write to 0xffff8881027e8518 of 8 bytes by task 14820 on cpu 0:
 percpu_counter_add_batch+0x9c/0xd0 lib/percpu_counter.c:91
 __add_wb_stat include/linux/backing-dev.h:70 [inline]
 inc_wb_stat include/linux/backing-dev.h:75 [inline]
 account_page_dirtied+0x1fe/0x2e0 mm/page-writeback.c:2458
 __set_page_dirty+0xbc/0x1a0 mm/page-writeback.c:2500
 mark_buffer_dirty+0x126/0x200 fs/buffer.c:1108
 __block_commit_write fs/buffer.c:2083 [inline]
 block_write_end+0x13d/0x260 fs/buffer.c:2162
 generic_write_end+0x5e/0x180 fs/buffer.c:2176
 ext4_da_write_end+0x4cc/0x5e0 fs/ext4/inode.c:3062
 generic_perform_write+0x251/0x3e0 mm/filemap.c:3781
 ext4_buffered_write_iter+0x305/0x400 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11f0
 call_write_iter include/linux/fs.h:2163 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x7bc/0x900 fs/read_write.c:594
 ksys_write+0xd9/0x190 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881027e8518 of 8 bytes by task 57 on cpu 1:
 percpu_counter_read include/linux/percpu_counter.h:72 [inline]
 __wb_update_bandwidth+0x87/0x470 mm/page-writeback.c:1352
 wb_update_bandwidth+0x46/0x70 mm/page-writeback.c:1380
 wb_update_bandwidth_workfn+0x18/0x20 mm/backing-dev.c:279
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

value changed: 0x00000000005ea930 -> 0x00000000005ea940

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 57 Comm: kworker/u4:2 Tainted: G        W         5.15.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_update_bandwidth_workfn
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