syzbot

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BUG: KCSAN: data-race in generic_write_end / mpage_process_page_bufs

write to 0xffff88810b176bd8 of 8 bytes by task 6422 on cpu 0:
 i_size_write include/linux/fs.h:886 [inline]
 generic_write_end+0xb1/0x350 fs/buffer.c:2168
 ext4_da_write_end+0x26c/0x620 fs/ext4/inode.c:3175
 generic_perform_write+0x264/0x3f0 mm/filemap.c:3783
 ext4_buffered_write_iter+0x235/0x3e0 fs/ext4/file.c:285
 ext4_file_write_iter+0x2bb/0x11b0
 __kernel_write_iter+0x157/0x380 fs/read_write.c:517
 dump_emit_page+0x3de/0x830 fs/coredump.c:864
 dump_user_range+0x5e/0x200 fs/coredump.c:915
 elf_core_dump+0x1b4f/0x1c60 fs/binfmt_elf.c:2137
 do_coredump+0xed7/0x1790 fs/coredump.c:762
 get_signal+0xa04/0xc70 kernel/signal.c:2845
 arch_do_signal_or_restart+0x85/0x290 arch/x86/kernel/signal.c:306
 exit_to_user_mode_loop+0x78/0x130 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0x69/0x90 kernel/entry/common.c:203
 irqentry_exit_to_user_mode+0x5/0x10 kernel/entry/common.c:309
 irqentry_exit+0xe/0x40 kernel/entry/common.c:412
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570

read to 0xffff88810b176bd8 of 8 bytes by task 3139 on cpu 1:
 i_size_read include/linux/fs.h:864 [inline]
 mpage_process_page_bufs+0x34/0x530 fs/ext4/inode.c:2221
 mpage_prepare_extent_to_map+0x6f5/0xcf0 fs/ext4/inode.c:2697
 ext4_do_writepages+0xa56/0x1e70 fs/ext4/inode.c:2875
 ext4_writepages+0x11b/0x240 fs/ext4/inode.c:2965
 do_writepages+0x1db/0x350 mm/page-writeback.c:2581
 __writeback_single_inode+0x81/0x590 fs/fs-writeback.c:1598
 writeback_sb_inodes+0x4dd/0xa30 fs/fs-writeback.c:1889
 wb_writeback+0x26b/0x650 fs/fs-writeback.c:2063
 wb_do_writeback+0x101/0x600 fs/fs-writeback.c:2206
 wb_workfn+0x88/0x260 fs/fs-writeback.c:2246
 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 arch/x86/entry/entry_64.S:308

value changed: 0x0000000002032000 -> 0x0000000002034000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3139 Comm: kworker/u4:7 Not tainted 6.2.0-rc6-syzkaller-00011-gc0b67534c95c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Workqueue: writeback wb_workfn (flush-8:0)
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