==================================================================
BUG: KCSAN: data-race in __wb_update_bandwidth / percpu_counter_add_batch

write to 0xffff8881026fb940 of 8 bytes by task 12434 on cpu 0:
 percpu_counter_add_batch+0xb4/0x130 lib/percpu_counter.c:91
 wb_stat_mod include/linux/backing-dev.h:70 [inline]
 __wb_writeout_add mm/page-writeback.c:592 [inline]
 __folio_end_writeback+0x274/0x580 mm/page-writeback.c:2814
 folio_end_writeback+0x58/0xd0 mm/filemap.c:1590
 end_page_writeback+0x37/0x50 mm/folio-compat.c:25
 ext4_finish_bio+0x3e2/0x430 fs/ext4/page-io.c:143
 ext4_release_io_end+0x98/0x200 fs/ext4/page-io.c:158
 ext4_end_io_end fs/ext4/page-io.c:192 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:257 [inline]
 ext4_end_io_rsv_work+0x306/0x360 fs/ext4/page-io.c:271
 process_one_work+0x3fc/0x980 kernel/workqueue.c:2297
 worker_thread+0x616/0xa70 kernel/workqueue.c:2444
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

read to 0xffff8881026fb940 of 8 bytes by task 16809 on cpu 1:
 percpu_counter_read include/linux/percpu_counter.h:72 [inline]
 __wb_update_bandwidth+0x9f/0x420 mm/page-writeback.c:1353
 wb_update_bandwidth mm/page-writeback.c:1380 [inline]
 do_writepages+0x2f1/0x320 mm/page-writeback.c:2379
 filemap_fdatawrite_wbc mm/filemap.c:399 [inline]
 __filemap_fdatawrite_range mm/filemap.c:432 [inline]
 file_write_and_wait_range+0x132/0x1d0 mm/filemap.c:809
 ext4_sync_file+0x105/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:182
 generic_write_sync include/linux/fs.h:2955 [inline]
 ext4_buffered_write_iter+0x322/0x380 fs/ext4/file.c:277
 ext4_file_write_iter+0x2e7/0x11f0
 call_write_iter include/linux/fs.h:2161 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_writev fs/read_write.c:924 [inline]
 do_pwritev+0x235/0x440 fs/read_write.c:1021
 __do_sys_pwritev fs/read_write.c:1068 [inline]
 __se_sys_pwritev fs/read_write.c:1063 [inline]
 __x64_sys_pwritev+0x54/0x60 fs/read_write.c:1063
 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

value changed: 0x000000000004e5e0 -> 0x000000000004e600

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16809 Comm: syz-executor.3 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================