Re: [PATCH] page-alloc: fix initialization of cross-node regions

[Julien Grall <julien.grall.oss@xxxxxxxxx>]

Hi Jan,

(Sorry for the formatting)

On Mon, 25 Jul 2022, 14:10 Jan Beulich, <jbeulich@xxxxxxxx> wrote:

Quite obviously to determine the split condition successive pages'
attributes need to be evaluated, not always those of the initial page.

Fixes: 72b02bc75b47 ("xen/heap: pass order to free_heap_pages() in heap init")
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Part of the problem was already introduced in 24a53060bd37 ("xen/heap:
Split init_heap_pages() in two"), but there it was still benign.

Is this because range will never cross numa node? How about the fake NUMA node?

--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -1885,11 +1885,11 @@ static void init_heap_pages(
              * range to cross zones.
              */
 #ifdef CONFIG_SEPARATE_XENHEAP
-            if ( zone != page_to_zone(pg) )
+            if ( zone != page_to_zone(pg + contig_pages) )
                 break;
 #endif

-            if ( nid != (phys_to_nid(page_to_maddr(pg))) )
+            if ( nid != (phys_to_nid(page_to_maddr(pg + contig_pages))) )
                 break;
         }

Hmmm I am not sure why I didn't spot this issue during my testing. It looks like this was introduced in v2, sorry for that.

Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheets,