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BUG: KCSAN: data-race in fprop_new_period / fprop_reflect_period_percpu

read-write to 0xffffffff86e8f418 of 4 bytes by interrupt on cpu 1:
 fprop_new_period+0xf7/0x170 lib/flex_proportions.c:83
 writeout_period+0x55/0xe0 mm/page-writeback.c:610
 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1421
 expire_timers+0x116/0x240 kernel/time/timer.c:1466
 __run_timers+0x350/0x400 kernel/time/timer.c:1737
 run_timer_softirq+0x56/0x60 kernel/time/timer.c:1752
 __do_softirq+0x158/0x2e3 kernel/softirq.c:558
 run_ksoftirqd+0x1f/0x30 kernel/softirq.c:921
 smpboot_thread_fn+0x308/0x4a0 kernel/smpboot.c:164
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffffffff86e8f418 of 4 bytes by task 1833 on cpu 0:
 fprop_reflect_period_percpu+0x22/0x1a0 lib/flex_proportions.c:192
 __fprop_add_percpu lib/flex_proportions.c:223 [inline]
 __fprop_add_percpu_max+0x54/0x180 lib/flex_proportions.c:281
 wb_domain_writeout_add mm/page-writeback.c:557 [inline]
 __wb_writeout_add+0x7e/0x1d0 mm/page-writeback.c:581
 __folio_end_writeback+0x2f4/0x540 mm/page-writeback.c:2809
 folio_end_writeback+0x57/0x130 mm/filemap.c:1646
 end_page_writeback+0x3b/0xe0 mm/folio-compat.c:26
 ext4_finish_bio+0x33e/0x420 fs/ext4/page-io.c:145
 ext4_release_io_end+0x5f/0x140 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+0x206/0x280 fs/ext4/page-io.c:273
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

value changed: 0x0000001d -> 0x0000001e

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1833 Comm: kworker/u4:3 Not tainted 5.18.0-rc5-syzkaller-00028-ga7391ad35724-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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FAT-fs (loop1): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)