[PATCH] Fix binfmt_misc locking

This fixes a sleep-in-spinlock bug for binfmt_misc registration.

That lock is purely for the list, not for the dentry.

fs/binfmt_misc.c

@@ -529,8 +529,8 @@ static ssize_t bm_register_write(struct file *file, const char *buffer,
 	inode->u.generic_ip = e;
 	inode->i_fop = &bm_entry_operations;
 
-	write_lock(&entries_lock);
 	d_instantiate(dentry, inode);
+	write_lock(&entries_lock);
 	list_add(&e->list, &entries);
 	write_unlock(&entries_lock);
 

mm/filemap.c

@@ -82,6 +82,9 @@
  *    ->private_lock		(try_to_unmap_one)
  *    ->page_lock		(try_to_unmap_one)
  *    ->zone.lru_lock		(follow_page->mark_page_accessed)
+ *
+ *  ->task->proc_lock
+ *    ->dcache_lock		(proc_pid_lookup)
  */
 
 /*