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BUG: KCSAN: data-race in fprop_new_period / fprop_reflect_period_percpu

read-write to 0xffffffff86f7db90 of 4 bytes by interrupt on cpu 1:
 fprop_new_period+0xaa/0xe0 lib/flex_proportions.c:79
 writeout_period+0x59/0xe0 mm/page-writeback.c:613
 call_timer_fn+0x35/0x290 kernel/time/timer.c:1700
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x46c/0x650 kernel/time/timer.c:2022
 run_timer_softirq+0x31/0x40 kernel/time/timer.c:2037
 __do_softirq+0xc1/0x265 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+0x6d/0x80 arch/x86/kernel/apic/apic.c:1109
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
 __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:95 [inline]
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irq+0x2f/0x40 kernel/locking/spinlock.c:202
 spin_unlock_irq include/linux/spinlock.h:400 [inline]
 filemap_remove_folio+0x74/0x210 mm/filemap.c:261
 truncate_inode_folio+0x19f/0x1e0 mm/truncate.c:196
 truncate_inode_pages_range+0x6ea/0x800 mm/truncate.c:425
 truncate_inode_pages mm/truncate.c:449 [inline]
 truncate_inode_pages_final+0x58/0x60 mm/truncate.c:484
 ext4_evict_inode+0x174/0xdc0 fs/ext4/inode.c:193
 evict+0x1aa/0x410 fs/inode.c:665
 iput_final fs/inode.c:1789 [inline]
 iput+0x42c/0x5b0 fs/inode.c:1815
 dentry_unlink_inode+0x22a/0x240 fs/dcache.c:401
 __dentry_kill+0x2db/0x4a0 fs/dcache.c:607
 dentry_kill+0x8d/0x1e0
 dput+0x118/0x1f0 fs/dcache.c:913
 __fput+0x475/0x600 fs/file_table.c:392
 ____fput+0x15/0x20 fs/file_table.c:412
 task_work_run+0x135/0x1a0 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x5ff/0x1670 kernel/exit.c:874
 do_group_exit+0x101/0x150 kernel/exit.c:1024
 get_signal+0xeb7/0xff0 kernel/signal.c:2877
 arch_do_signal_or_restart+0x89/0x2a0 arch/x86/kernel/signal.c:308
 exit_to_user_mode_loop+0x6f/0xe0 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
 irqentry_exit_to_user_mode+0x9/0x20 kernel/entry/common.c:310
 irqentry_exit+0x12/0x40 kernel/entry/common.c:413
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

read to 0xffffffff86f7db90 of 4 bytes by task 3603 on cpu 0:
 fprop_reflect_period_percpu+0x22/0x1a0 lib/flex_proportions.c:188
 __fprop_add_percpu lib/flex_proportions.c:219 [inline]
 __fprop_add_percpu_max+0x58/0x180 lib/flex_proportions.c:277
 wb_domain_writeout_add mm/page-writeback.c:560 [inline]
 __wb_writeout_add+0x7e/0x1d0 mm/page-writeback.c:584
 __folio_end_writeback+0x26f/0x500 mm/page-writeback.c:2983
 folio_end_writeback+0x5b/0x150 mm/filemap.c:1616
 ext4_finish_bio+0x3f2/0x870 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+0x434/0x860 kernel/workqueue.c:2597
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2748
 kthread+0x1d7/0x210 kernel/kthread.c:389
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

value changed: 0x00000095 -> 0x00000096

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3603 Comm: kworker/u4:7 Not tainted 6.4.0-syzkaller-11311-g24be4d0b46bb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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