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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
 constant_test_bit arch/x86/include/asm/bitops.h:207 [inline]
 arch_test_bit arch/x86/include/asm/bitops.h:239 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
 set_buffer_meta include/linux/buffer_head.h:134 [inline]
 __ext4_handle_dirty_metadata+0x34/0x470 fs/ext4/ext4_jbd2.c:351
 ext4_do_update_inode fs/ext4/inode.c:5257 [inline]
 ext4_mark_iloc_dirty+0xaa9/0xe10 fs/ext4/inode.c:5877
 __ext4_mark_inode_dirty+0x314/0x440 fs/ext4/inode.c:6081
 ext4_dirty_inode+0x91/0xb0 fs/ext4/inode.c:6110
 __mark_inode_dirty+0x169/0x7d0 fs/fs-writeback.c:2419
 mark_inode_dirty include/linux/fs.h:2465 [inline]
 generic_write_end+0x18e/0x360 fs/buffer.c:2184
 ext4_da_write_end+0x4bd/0x630 fs/ext4/inode.c:3175
 generic_perform_write+0x253/0x3d0 mm/filemap.c:3784
 ext4_buffered_write_iter+0x234/0x3e0 fs/ext4/file.c:285
 ext4_file_write_iter+0x2d2/0x1270
 __kernel_write_iter+0x15c/0x380 fs/read_write.c:517
 dump_emit_page fs/coredump.c:888 [inline]
 dump_user_range+0x25b/0x490 fs/coredump.c:915
 elf_core_dump+0x1a73/0x1b90 fs/binfmt_elf.c:2137
 do_coredump+0xfeb/0x1800 fs/coredump.c:762
 get_signal+0xd65/0xfe0 kernel/signal.c:2845
 arch_do_signal_or_restart+0x89/0x2b0 arch/x86/kernel/signal.c:306
 exit_to_user_mode_loop+0x6d/0xe0 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0x6a/0xa0 kernel/entry/common.c:203
 irqentry_exit_to_user_mode+0x9/0x20 kernel/entry/common.c:309
 irqentry_exit+0x12/0x40 kernel/entry/common.c:412
 exc_general_protection+0x339/0x4c0 arch/x86/kernel/traps.c:728
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:564

read to 0xffffffff86e570c0 of 4 bytes by task 11862 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: 0x0000014f -> 0x00000150

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11862 Comm: kworker/u4:14 Not tainted 6.2.0-rc8-syzkaller-00151-g925cf0457d7e-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
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