syzbot

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BUG: KCSAN: data-race in generic_write_end / mpage_process_page_bufs

write to 0xffff88812190e648 of 8 bytes by task 7354 on cpu 0:
 i_size_write include/linux/fs.h:886 [inline]
 generic_write_end+0xb1/0x350 fs/buffer.c:2183
 ext4_da_write_end+0x26c/0x620 fs/ext4/inode.c:3089
 generic_perform_write+0x264/0x3f0 mm/filemap.c:3749
 ext4_buffered_write_iter+0x235/0x3e0 fs/ext4/file.c:270
 ext4_file_write_iter+0x2e3/0x1210
 call_write_iter include/linux/fs.h:2187 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:584
 ksys_write+0xe8/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:646
 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+0x63/0xcd

read to 0xffff88812190e648 of 8 bytes by task 7359 on cpu 1:
 i_size_read include/linux/fs.h:864 [inline]
 mpage_process_page_bufs+0x34/0x530 fs/ext4/inode.c:2206
 mpage_prepare_extent_to_map+0x5b7/0xa50 fs/ext4/inode.c:2653
 ext4_writepages+0x9b8/0x1cf0 fs/ext4/inode.c:2825
 do_writepages+0x1db/0x350 mm/page-writeback.c:2468
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 file_write_and_wait_range+0xd6/0x170 mm/filemap.c:773
 ext4_sync_file+0x105/0x6d0 fs/ext4/fsync.c:151
 vfs_fsync_range fs/sync.c:188 [inline]
 vfs_fsync fs/sync.c:202 [inline]
 do_fsync fs/sync.c:212 [inline]
 __do_sys_fdatasync fs/sync.c:225 [inline]
 __se_sys_fdatasync fs/sync.c:223 [inline]
 __x64_sys_fdatasync+0x7a/0xd0 fs/sync.c:223
 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+0x63/0xcd

value changed: 0x0000000000416000 -> 0x0000000000418000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7359 Comm: syz-executor.2 Not tainted 6.0.0-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
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