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BUG: KCSAN: data-race in ext4_write_end / mpage_process_page_bufs

write to 0xffff888100424a88 of 8 bytes by task 24661 on cpu 1:
 i_size_write include/linux/fs.h:916 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3421 [inline]
 ext4_write_end+0x16e/0x6f0 fs/ext4/inode.c:1303
 ext4_da_write_end+0x6d/0x5e0 fs/ext4/inode.c:3029
 generic_perform_write+0x251/0x3e0 mm/filemap.c:3781
 ext4_buffered_write_iter+0x305/0x400 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11f0
 call_write_iter include/linux/fs.h:2163 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x7bc/0x900 fs/read_write.c:594
 ksys_write+0xd9/0x190 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888100424a88 of 8 bytes by task 24675 on cpu 0:
 i_size_read include/linux/fs.h:894 [inline]
 mpage_process_page_bufs+0x34/0x560 fs/ext4/inode.c:2190
 mpage_prepare_extent_to_map+0x4f6/0x650 fs/ext4/inode.c:2624
 ext4_writepages+0xa18/0x1d70 fs/ext4/inode.c:2796
 do_writepages+0x26b/0x3c0 mm/page-writeback.c:2364
 filemap_fdatawrite_wbc mm/filemap.c:400 [inline]
 __filemap_fdatawrite_range mm/filemap.c:433 [inline]
 file_write_and_wait_range+0x1ae/0x240 mm/filemap.c:810
 ext4_sync_file+0x105/0x670 fs/ext4/fsync.c:151
 vfs_fsync_range fs/sync.c:200 [inline]
 vfs_fsync fs/sync.c:214 [inline]
 do_fsync fs/sync.c:224 [inline]
 __do_sys_fdatasync fs/sync.c:237 [inline]
 __se_sys_fdatasync fs/sync.c:235 [inline]
 __x64_sys_fdatasync+0x7a/0xd0 fs/sync.c:235
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000163000 -> 0x0000000000165000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24675 Comm: syz-executor.5 Not tainted 5.15.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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