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BUG: KCSAN: data-race in generic_write_end / mpage_process_page_bufs

write to 0xffff88810635b838 of 8 bytes by task 5182 on cpu 0:
 i_size_write include/linux/fs.h:901 [inline]
 generic_write_end+0x9f/0x240 fs/buffer.c:2304
 ext4_da_write_end+0x49e/0x700 fs/ext4/inode.c:2988
 generic_perform_write+0x26d/0x410 mm/filemap.c:3934
 ext4_buffered_write_iter+0x1f6/0x370 fs/ext4/file.c:299
 ext4_file_write_iter+0x283/0x1230
 __kernel_write_iter+0x162/0x3c0 fs/read_write.c:517
 dump_emit_page fs/coredump.c:888 [inline]
 dump_user_range+0x25d/0x490 fs/coredump.c:915
 elf_core_dump+0x1a85/0x1ba0 fs/binfmt_elf.c:2142
 do_coredump+0x1029/0x1890 fs/coredump.c:764
 get_signal+0xd65/0xff0 kernel/signal.c:2867
 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
 exc_general_protection+0x339/0x4c0 arch/x86/kernel/traps.c:731
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:564

read to 0xffff88810635b838 of 8 bytes by task 3114 on cpu 1:
 i_size_read include/linux/fs.h:879 [inline]
 mpage_process_page_bufs+0x34/0x5e0 fs/ext4/inode.c:1956
 mpage_prepare_extent_to_map+0x794/0xb90 fs/ext4/inode.c:2487
 ext4_do_writepages+0xa5e/0x21e0 fs/ext4/inode.c:2675
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2766
 do_writepages+0x1c5/0x340 mm/page-writeback.c:2553
 __writeback_single_inode+0x91/0x860 fs/fs-writeback.c:1603
 writeback_sb_inodes+0x511/0xaa0 fs/fs-writeback.c:1894
 wb_writeback+0x252/0x6e0 fs/fs-writeback.c:2070
 wb_do_writeback fs/fs-writeback.c:2217 [inline]
 wb_workfn+0x1a8/0x8d0 fs/fs-writeback.c:2257
 process_one_work+0x434/0x860 kernel/workqueue.c:2600
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2751
 kthread+0x1d7/0x210 kernel/kthread.c:389
 ret_from_fork+0x2e/0x40 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x000000000225e000 -> 0x0000000002260000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3114 Comm: kworker/u4:5 Not tainted 6.5.0-rc5-syzkaller-00362-ga785fd28d31f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: writeback wb_workfn (flush-8:0)
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