On Fri, Dec 02, 2022 at 04:58:42PM +0000, Matthew Wilcox wrote:
> Landing on 793917d997df makes a lot more sense. That's where we
> actually start using large folios. It doesn't really help narrow
> down the problem. I have an idea for what it might be; patch to
> try will follow. But I'll need feedback by email.
This will give us a bit more information when it does happen.
Further patch to catch it earlier will come "soon".
diff --git a/lib/xarray.c b/lib/xarray.c
index 6f47f6375808..b358b4e1dac6 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -6,6 +6,7 @@
* Author: Matthew Wilcox <willy@xxxxxxxxxxxxx>
*/
+#define XA_DEBUG
#include <linux/bitmap.h>
#include <linux/export.h>
#include <linux/list.h>
@@ -207,6 +208,12 @@ static void *xas_descend(struct xa_state *xas, struct xa_node *node)
if (xa_is_sibling(entry)) {
offset = xa_to_sibling(entry);
entry = xa_entry(xas->xa, node, offset);
+
+ if (xa_is_sibling(entry)) {
+ printk("***BAD SIBLING*** index %ld offset %d\n",
+ xas->xa_index, offset);
+ xa_dump_node(node);
+ }
}
xas->xa_offset = offset;
