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BUG: KCSAN: data-race in fprop_new_period / fprop_reflect_period_percpu

read-write to 0xffffffff86f3e070 of 4 bytes by interrupt on cpu 0:
 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+0x5a/0x60 kernel/time/timer.c:2037
 __do_softirq+0xe4/0x2b0 kernel/softirq.c:571
 run_ksoftirqd+0x23/0x30 kernel/softirq.c:934
 smpboot_thread_fn+0x2f8/0x490 kernel/smpboot.c:164
 kthread+0x1ac/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

read to 0xffffffff86f3e070 of 4 bytes by task 35 on cpu 1:
 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:3023
 folio_end_writeback+0x5b/0x150 mm/filemap.c:1618
 end_page_writeback+0x44/0xf0 mm/folio-compat.c:27
 __block_write_full_page+0x598/0xb00 fs/buffer.c:1850
 block_write_full_page+0x1d8/0x200
 blkdev_writepage+0x24/0x30 block/fops.c:391
 writepage_cb+0x3c/0xd0 mm/page-writeback.c:2535
 write_cache_pages+0x39b/0x760 mm/page-writeback.c:2473
 do_writepages+0x212/0x340 mm/page-writeback.c:2556
 __writeback_single_inode+0x91/0x860 fs/fs-writeback.c:1600
 writeback_sb_inodes+0x515/0xaa0 fs/fs-writeback.c:1891
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:1962
 wb_writeback+0x24d/0x6c0 fs/fs-writeback.c:2067
 wb_check_old_data_flush fs/fs-writeback.c:2167 [inline]
 wb_do_writeback fs/fs-writeback.c:2220 [inline]
 wb_workfn+0x615/0x8d0 fs/fs-writeback.c:2248
 process_one_work+0x3e6/0x750 kernel/workqueue.c:2390
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2537
 kthread+0x1ac/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

value changed: 0x00000011 -> 0x00000012

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 35 Comm: kworker/u4:2 Not tainted 6.3.0-rc4-syzkaller-00243-g6ab608fe852b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: writeback wb_workfn (flush-8:0)
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