syzbot

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BUG: KCSAN: data-race in __wb_writeout_add / writeout_period

write to 0xffffffff88404f68 of 8 bytes by interrupt on cpu 1:
 writeout_period+0xa6/0xe0 mm/page-writeback.c:614
 call_timer_fn+0x3a/0x300 kernel/time/timer.c:1793
 expire_timers kernel/time/timer.c:1844 [inline]
 __run_timers kernel/time/timer.c:2418 [inline]
 __run_timer_base+0x417/0x640 kernel/time/timer.c:2429
 run_timer_base kernel/time/timer.c:2438 [inline]
 run_timer_softirq+0x45/0x70 kernel/time/timer.c:2449
 __do_softirq+0xc8/0x285 kernel/softirq.c:554
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu kernel/softirq.c:633 [inline]
 irq_exit_rcu+0x3c/0x90 kernel/softirq.c:645
 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
 next_uptodate_folio+0x5e6/0x7a0 mm/filemap.c:3465
 filemap_map_pages+0x708/0x900 mm/filemap.c:3612
 do_fault_around mm/memory.c:4852 [inline]
 do_read_fault mm/memory.c:4885 [inline]
 do_fault mm/memory.c:5024 [inline]
 do_pte_missing mm/memory.c:3880 [inline]
 handle_pte_fault mm/memory.c:5300 [inline]
 __handle_mm_fault mm/memory.c:5441 [inline]
 handle_mm_fault+0x1060/0x27e0 mm/memory.c:5606
 do_user_addr_fault arch/x86/mm/fault.c:1362 [inline]
 handle_page_fault arch/x86/mm/fault.c:1505 [inline]
 exc_page_fault+0x3eb/0x6d0 arch/x86/mm/fault.c:1563
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

read to 0xffffffff88404f68 of 8 bytes by task 27 on cpu 0:
 wb_domain_writeout_add mm/page-writeback.c:563 [inline]
 __wb_writeout_add+0x8a/0x1e0 mm/page-writeback.c:584
 __folio_end_writeback+0x21b/0x4a0 mm/page-writeback.c:3017
 folio_end_writeback+0x74/0x1f0 mm/filemap.c:1608
 ext4_finish_bio+0x47b/0x8f0 fs/ext4/page-io.c:145
 ext4_release_io_end+0x8c/0x1f0 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+0x2d3/0x370 fs/ext4/page-io.c:273
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
 worker_thread+0x526/0x730 kernel/workqueue.c:3416
 kthread+0x1d1/0x210 kernel/kthread.c:388
 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: 0x00000000ffffb9f5 -> 0x00000000ffffbb21

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 27 Comm: kworker/u8:1 Not tainted 6.9.0-rc5-syzkaller-00159-gc942a0cd3603 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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