Re: [syzbot] [ntfs3?] possible deadlock in ntfs_file_mmap

[Hillf Danton]

On Sat, 27 Jul 2024 06:44:20 -0700
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    2f8c4f506285 Merge tag 'auxdisplay-for-v6.11-tag1' of git:..
> git tree:       upstream
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12e875a1980000

#syz test upstream  2f8c4f506285

--- x/fs/ntfs3/file.c
+++ y/fs/ntfs3/file.c
@@ -365,7 +365,10 @@ static int ntfs_file_mmap(struct file *f
 		}
 
 		if (ni->i_valid < to) {
-			inode_lock(inode);
+			if (!inode_trylock(inode)) {
+				err = -EDEADLK;
+				goto out;
+			}
 			err = ntfs_extend_initialized_size(file, ni,
 							   ni->i_valid, to);
 			inode_unlock(inode);
--