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Re: [PATCH 2/2] xen/mm: Fix off-by-one stopping tail merge in reserve_offlined_page
- To: Bernhard Kaindl <bernhard.kaindl@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 2 Jun 2026 16:43:25 +0200
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- Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Julien Grall <julien@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 02 Jun 2026 14:43:26 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 28.05.2026 16:55, Bernhard Kaindl wrote:
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -1427,11 +1427,13 @@ static int reserve_offlined_page(struct page_info
> *head)
>
> next_order = cur_order = 0;
>
> + /* Attempt to grow the order (size) of the buddy as much as
> possible. */
> while ( cur_order < head_order )
> {
> next_order = cur_order + 1;
>
> - if ( (cur_head + (1 << next_order)) >= (head + ( 1 <<
> head_order)) )
> + /* Do not grow to next_order if it would go beyond the buddy. */
> + if ( (cur_head + (1 << next_order)) > (head + ( 1 <<
> head_order)) )
> goto merge;
>
> /* Do not grow to next_order if cur_head is not aligned to it. */
Much like for the other series: With this coming first (and separate from the
new test), with the stray blank removed from the line that you touch, and with
parentheses also added to reserve_offlined_page() in the subject (like you
have it in the description):
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Maybe also s/stopping/preventing/ in the subject?
Jan
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