==================================================================
BUG: KCSAN: data-race in fprop_new_period / fprop_reflect_period_percpu

read-write to 0xffffffff86e570c0 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
 invoke_softirq kernel/softirq.c:445 [inline]
 __irq_exit_rcu+0x85/0x100 kernel/softirq.c:650
 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1107
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649
 __sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:203
 ext4_map_blocks+0xa8d/0x1050 fs/ext4/inode.c:717
 ext4_alloc_file_blocks+0x272/0x6d0 fs/ext4/extents.c:4470
 ext4_fallocate+0x802/0x12b0 fs/ext4/extents.c:4757
 vfs_fallocate+0x369/0x3d0 fs/open.c:324
 do_vfs_ioctl+0x12a1/0x1360 fs/ioctl.c:849
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x81/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86e570c0 of 4 bytes by task 30388 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:3044
 folio_end_writeback+0x5b/0x150 mm/filemap.c:1614
 end_page_writeback+0x44/0xf0 mm/folio-compat.c:26
 ext4_finish_bio+0x3d8/0x4d0 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+0x3e6/0x750 kernel/workqueue.c:2289
 worker_thread+0x5ef/0xa10 kernel/workqueue.c:2436
 kthread+0x1ac/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

value changed: 0x000000e7 -> 0x000000e8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 30388 Comm: kworker/u4:5 Not tainted 6.2.0-syzkaller-00081-g91bc559d8d3a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
==================================================================