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Re: [Xen-devel] [PATCH 2/8] x86/setup: Fix badpage= handling for memory above HYPERVISOR_VIRT_END
- To: David Woodhouse <dwmw2@xxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Julien Grall <julien@xxxxxxx>
- Date: Fri, 6 Mar 2020 22:52:44 +0000
- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Varad Gautam <vrd@xxxxxxxxx>, Ian Jackson <ian.jackson@xxxxxxxxxxxxx>, Hongyan Xia <hongyxia@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Paul Durrant <pdurrant@xxxxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Delivery-date: Fri, 06 Mar 2020 22:53:12 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
Hi David,
On 01/02/2020 00:32, David Woodhouse wrote:
/*
* Hand the specified arbitrary page range to the specified heap zone
* checking the node_id of the previous page. If they differ and the
@@ -1799,18 +1811,23 @@ static void init_heap_pages(
{
unsigned int nid = phys_to_nid(page_to_maddr(pg+i));
+ /* If the (first) page is already marked broken, don't add it. */
+ if ( pg[i].count_info & PGC_broken )
+ continue;
+
if ( unlikely(!avail[nid]) )
{
+ unsigned long contig_nr_pages = contig_avail_pages(pg + i,
nr_pages);
I spent the evening chasing a bug due to this change. Xen may give to
init_heap_pages() a range that crosses NUMA node.
contig_avail_pages will go through the range [pg + 1, pg + i +
nr_pages). As nr_pages corresponds to the number of pages in the
original range, we may overrun the frametable and crash.
So I think you want to use contig_avail_pages(pg + i, nr_pages - i).
Cheers,
--
Julien Grall
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