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BUG: KCSAN: data-race in ext4_write_end / mpage_process_page_bufs

write to 0xffff888139ccec48 of 8 bytes by task 12861 on cpu 0:
 i_size_write include/linux/fs.h:913 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3422 [inline]
 ext4_write_end+0x16d/0x710 fs/ext4/inode.c:1303
 ext4_da_write_end+0x6d/0x630 fs/ext4/inode.c:3026
 generic_perform_write+0x261/0x400 mm/filemap.c:3767
 ext4_buffered_write_iter+0x25b/0x380 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x1200
 call_write_iter include/linux/fs.h:2162 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_writev fs/read_write.c:924 [inline]
 do_pwritev+0x235/0x440 fs/read_write.c:1021
 __do_sys_pwritev fs/read_write.c:1068 [inline]
 __se_sys_pwritev fs/read_write.c:1063 [inline]
 __x64_sys_pwritev+0x54/0x60 fs/read_write.c:1063
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888139ccec48 of 8 bytes by task 12872 on cpu 1:
 i_size_read include/linux/fs.h:891 [inline]
 mpage_process_page_bufs+0x34/0x560 fs/ext4/inode.c:2187
 mpage_prepare_extent_to_map+0x4f6/0x650 fs/ext4/inode.c:2621
 ext4_writepages+0xa78/0x1e80 fs/ext4/inode.c:2793
 do_writepages+0x1cb/0x330 mm/page-writeback.c:2364
 filemap_fdatawrite_wbc mm/filemap.c:407 [inline]
 __filemap_fdatawrite_range mm/filemap.c:440 [inline]
 filemap_write_and_wait_range+0x1b2/0x340 mm/filemap.c:718
 filemap_write_and_wait include/linux/fs.h:2865 [inline]
 ext4_bmap+0x124/0x230 fs/ext4/inode.c:3139
 bmap+0x5c/0x80 fs/inode.c:1721
 ioctl_fibmap fs/ioctl.c:77 [inline]
 file_ioctl fs/ioctl.c:331 [inline]
 do_vfs_ioctl+0x1330/0x14a0 fs/ioctl.c:853
 __do_sys_ioctl fs/ioctl.c:872 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000040f1000 -> 0x00000000040f2000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12872 Comm: syz-executor.0 Not tainted 5.16.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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