mm/huge_memory: Fix xarray node memory leak
If xas_split_alloc() fails to allocate the necessary nodes to complete the
xarray entry split, it sets the xa_state to -ENOMEM, which xas_nomem()
then interprets as "Please allocate more memory", not as "Please free
any unnecessary memory" (which was the intended outcome). It's confusing
to use xas_nomem() to free memory in this context, so call xas_destroy()
instead.
Reported-by: syzbot+9e27a75a8c24f3fe75c1@syzkaller.appspotmail.com
Fixes: 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
diff --git a/lib/xarray.c b/lib/xarray.c
index 54e646e..ea9ce1f 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -264,9 +264,10 @@ static void xa_node_free(struct xa_node *node)
* xas_destroy() - Free any resources allocated during the XArray operation.
* @xas: XArray operation state.
*
- * This function is now internal-only.
+ * Most users will not need to call this function; it is called for you
+ * by xas_nomem().
*/
-static void xas_destroy(struct xa_state *xas)
+void xas_destroy(struct xa_state *xas)
{
struct xa_node *next, *node = xas->xa_alloc;
