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BUG: KCSAN: data-race in ext4_writepages / generic_write_end

write to 0xffff8881210b97c8 of 8 bytes by task 4661 on cpu 1:
 i_size_write include/linux/fs.h:878 [inline]
 generic_write_end+0x98/0x230 fs/buffer.c:2183
 ext4_da_write_end+0x26c/0x620 fs/ext4/inode.c:3068
 generic_perform_write+0x26a/0x3f0 mm/filemap.c:3798
 ext4_buffered_write_iter+0x222/0x330 fs/ext4/file.c:270
 ext4_file_write_iter+0x2e3/0x1210
 call_write_iter include/linux/fs.h:2050 [inline]
 new_sync_write fs/read_write.c:504 [inline]
 vfs_write+0x71c/0x890 fs/read_write.c:591
 ksys_write+0xe8/0x1a0 fs/read_write.c:644
 __do_sys_write fs/read_write.c:656 [inline]
 __se_sys_write fs/read_write.c:653 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:653
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881210b97c8 of 8 bytes by task 4668 on cpu 0:
 i_size_read include/linux/fs.h:856 [inline]
 mpage_submit_page fs/ext4/inode.c:2084 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2336 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2475 [inline]
 ext4_writepages+0xfd9/0x1d00 fs/ext4/inode.c:2804
 do_writepages+0x1db/0x350 mm/page-writeback.c:2352
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 __filemap_fdatawrite mm/filemap.c:427 [inline]
 filemap_flush+0x93/0xc0 mm/filemap.c:454
 ext4_alloc_da_blocks+0x47/0x100 fs/ext4/inode.c:3112
 ext4_release_file+0x5b/0x1d0 fs/ext4/file.c:143
 __fput+0x292/0x510 fs/file_table.c:317
 ____fput+0x11/0x20 fs/file_table.c:350
 task_work_run+0x8e/0x110 kernel/task_work.c:164
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x124/0x130 kernel/entry/common.c:169
 exit_to_user_mode_prepare kernel/entry/common.c:201 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x6a/0x90 kernel/entry/common.c:294
 do_syscall_64+0x37/0x70 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000005f7000 -> 0x00000000005f9000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4668 Comm: syz-executor.3 Not tainted 5.18.0-rc6-syzkaller-00009-gfeb9c5e19e91 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/12/2022
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