Re: [syzbot] [kernfs?] possible deadlock in kernfs_fop_llseek

[Hillf Danton]

On Wed, 03 Apr 2024 11:23:26 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    fe46a7dd189e Merge tag 'sound-6.9-rc1' of git://git.kernel..
> git tree:       upstream
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15c38139180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  fe46a7dd189e

--- x/fs/overlayfs/util.c
+++ y/fs/overlayfs/util.c
@@ -1159,9 +1159,8 @@ int ovl_nlink_start(struct dentry *dentr
 			return err;
 	}
 
-	err = ovl_inode_lock_interruptible(inode);
-	if (err)
-		return err;
+	if (!mutex_trylock(&OVL_I(inode)->lock))
+		return -EBUSY;
 
 	err = ovl_want_write(dentry);
 	if (err)
--