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BUG: KCSAN: data-race in __wb_writeout_add / writeout_period

write to 0xffffffff87126d70 of 8 bytes by interrupt on cpu 1:
 writeout_period+0xa6/0xe0 mm/page-writeback.c:614
 call_timer_fn+0x37/0x2f0 kernel/time/timer.c:1700
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x448/0x630 kernel/time/timer.c:2038
 run_timer_softirq+0x31/0x40 kernel/time/timer.c:2053
 __do_softirq+0xc4/0x27b kernel/softirq.c:553
 invoke_softirq kernel/softirq.c:427 [inline]
 __irq_exit_rcu kernel/softirq.c:632 [inline]
 irq_exit_rcu+0x3b/0x90 kernel/softirq.c:644
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1076
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649
 kcsan_setup_watchpoint+0x3fe/0x410 kernel/kcsan/core.c:705
 bvec_set_page include/linux/bvec.h:47 [inline]
 __bio_add_page block/bio.c:1078 [inline]
 bio_add_page+0x206/0x2b0 block/bio.c:1113
 bio_add_folio+0x52/0x80 block/bio.c:1145
 io_submit_add_bh fs/ext4/page-io.c:423 [inline]
 ext4_bio_write_folio+0x8b5/0x9a0 fs/ext4/page-io.c:563
 mpage_submit_folio fs/ext4/inode.c:1869 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2115 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2254 [inline]
 ext4_do_writepages+0x139f/0x2100 fs/ext4/inode.c:2679
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2768
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 file_write_and_wait_range+0xf4/0x190 mm/filemap.c:779
 ext4_sync_file+0x133/0x6c0 fs/ext4/fsync.c:158
 vfs_fsync_range+0x111/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2734 [inline]
 ext4_buffered_write_iter+0x334/0x370 fs/ext4/file.c:305
 ext4_file_write_iter+0x297/0xe10
 call_write_iter include/linux/fs.h:2087 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0x760/0x8d0 fs/read_write.c:590
 ksys_write+0xeb/0x1a0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:652
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffffffff87126d70 of 8 bytes by task 10338 on cpu 0:
 wb_domain_writeout_add mm/page-writeback.c:563 [inline]
 __wb_writeout_add+0x8a/0x1d0 mm/page-writeback.c:584
 __folio_end_writeback+0x21b/0x4a0 mm/page-writeback.c:2963
 folio_end_writeback+0x74/0x1f0 mm/filemap.c:1599
 ext4_finish_bio+0x47b/0x8e0 fs/ext4/page-io.c:145
 ext4_release_io_end+0x8c/0x1e0 fs/ext4/page-io.c:160
 ext4_end_io_end fs/ext4/page-io.c:194 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:259 [inline]
 ext4_end_io_rsv_work+0x2d3/0x360 fs/ext4/page-io.c:273
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x5b8/0xa40 kernel/workqueue.c:2706
 worker_thread+0x525/0x730 kernel/workqueue.c:2787
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:243

value changed: 0x000000010000b35c -> 0x000000010000b488

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10338 Comm: kworker/u4:17 Not tainted 6.8.0-rc7-syzkaller-00051-g67be068d31d4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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