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BUG: KCSAN: data-race in __wb_writeout_add / writeout_period

write to 0xffffffff8841f118 of 8 bytes by interrupt on cpu 0:
 writeout_period+0xa6/0xe0 mm/page-writeback.c:614
 call_timer_fn+0x3a/0x300 kernel/time/timer.c:1792
 expire_timers kernel/time/timer.c:1843 [inline]
 __run_timers kernel/time/timer.c:2417 [inline]
 __run_timer_base+0x417/0x640 kernel/time/timer.c:2428
 run_timer_base kernel/time/timer.c:2437 [inline]
 run_timer_softirq+0x45/0x70 kernel/time/timer.c:2448
 handle_softirqs+0xc3/0x280 kernel/softirq.c:554
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu kernel/softirq.c:637 [inline]
 irq_exit_rcu+0x3e/0x90 kernel/softirq.c:649
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0x73/0x80 arch/x86/kernel/apic/apic.c:1043
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 kcsan_setup_watchpoint+0x404/0x410 kernel/kcsan/core.c:705
 __d_lookup_rcu+0x2a/0x290 fs/dcache.c:2172
 lookup_fast+0x8e/0x2a0 fs/namei.c:1627
 walk_component fs/namei.c:2000 [inline]
 link_path_walk+0x403/0x810 fs/namei.c:2331
 path_parentat fs/namei.c:2540 [inline]
 __filename_parentat+0x13c/0x3c0 fs/namei.c:2564
 filename_parentat fs/namei.c:2582 [inline]
 do_unlinkat+0x9b/0x4c0 fs/namei.c:4382
 __do_sys_unlink fs/namei.c:4455 [inline]
 __se_sys_unlink fs/namei.c:4453 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4453
 x64_sys_call+0x28a3/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff8841f118 of 8 bytes by task 5865 on cpu 1:
 wb_domain_writeout_add mm/page-writeback.c:563 [inline]
 __wb_writeout_add+0x83/0x1d0 mm/page-writeback.c:584
 __folio_end_writeback+0x215/0x4a0 mm/page-writeback.c:3042
 folio_end_writeback+0x74/0x1f0 mm/filemap.c:1632
 ext4_finish_bio+0x476/0x8e0 fs/ext4/page-io.c:144
 ext4_release_io_end+0x8c/0x1f0 fs/ext4/page-io.c:159
 ext4_end_io_end fs/ext4/page-io.c:193 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:258 [inline]
 ext4_end_io_rsv_work+0x2d3/0x370 fs/ext4/page-io.c:272
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
 worker_thread+0x526/0x730 kernel/workqueue.c:3393
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000000fffff4b4 -> 0x00000000fffff5e0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5865 Comm: kworker/u8:9 Not tainted 6.10.0-rc4-syzkaller-00035-g3d54351c64e8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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