[merged mm-stable] mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch removed from -mm tree

[merged mm-stable] mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/hugetlb: fix set_max_huge_pages() when there are surplus pages
has been removed from the -mm tree.  Its filename was
     mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Jinjiang Tu <tujinjiang@huawei.com>
Subject: mm/hugetlb: fix set_max_huge_pages() when there are surplus pages
Date: Tue, 25 Feb 2025 22:19:33 +0800

In set_max_huge_pages(), min_count should mean the acquired persistent
huge pages, but it contains surplus huge pages.  It will lead to failing
to free free huge pages for a node.

Steps to reproduce:
1) create 5 huge pages in Node 0
2) run a program to use all the huge pages
3) create 5 huge pages in Node 1
4) echo 0 > nr_hugepages for Node 1 to free the huge pages

The result:
        Node 0    Node 1
Total     5         5
Free      0         5
Surp      5         5

With this patch, step 4) destroys the 5 huge pages in Node 1

The result with this patch:
        Node 0    Node 1
Total     5         0
Free      0         0
Surp      5         0

Link: https://lkml.kernel.org/r/20250225141933.3852667-1-tujinjiang@huawei.com
Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes")
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/hugetlb.c~mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages
+++ a/mm/hugetlb.c
@@ -3937,7 +3937,7 @@ static int set_max_huge_pages(struct hst
 	 * and won't grow the pool anywhere else. Not until one of the
 	 * sysctls are changed, or the surplus pages go out of use.
 	 */
-	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
+	min_count = h->resv_huge_pages + persistent_huge_pages(h) - h->free_huge_pages;
 	min_count = max(count, min_count);
 	try_to_free_low(h, min_count, nodes_allowed);
 
_

Patches currently in -mm which might be from tujinjiang@huawei.com are

mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order.patch

Re: [merged mm-stable] mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch removed from -mm tree

[Jinjiang Tu]

在 2025/3/17 13:14, Andrew Morton 写道:
> The quilt patch titled
>       Subject: mm/hugetlb: fix set_max_huge_pages() when there are surplus pages
> has been removed from the -mm tree.  Its filename was
>       mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch
>
> This patch was dropped because it was merged into the mm-stable branch
> of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Hi, Andrew

As I explained in https://lore.kernel.org/all/c2c3d8b5-4b99-220e-20e0-e4a9dd8f5ecf@huawei.com/,
This patch fails to deal with free surplus huge pages, and will introduce another issue.

So please drop this patch from mm tree.

Thanks.

> ------------------------------------------------------
> From: Jinjiang Tu <tujinjiang@huawei.com>
> Subject: mm/hugetlb: fix set_max_huge_pages() when there are surplus pages
> Date: Tue, 25 Feb 2025 22:19:33 +0800
>
> In set_max_huge_pages(), min_count should mean the acquired persistent
> huge pages, but it contains surplus huge pages.  It will lead to failing
> to free free huge pages for a node.
>
> Steps to reproduce:
> 1) create 5 huge pages in Node 0
> 2) run a program to use all the huge pages
> 3) create 5 huge pages in Node 1
> 4) echo 0 > nr_hugepages for Node 1 to free the huge pages
>
> The result:
>          Node 0    Node 1
> Total     5         5
> Free      0         5
> Surp      5         5
>
> With this patch, step 4) destroys the 5 huge pages in Node 1
>
> The result with this patch:
>          Node 0    Node 1
> Total     5         0
> Free      0         0
> Surp      5         0
>
> Link: https://lkml.kernel.org/r/20250225141933.3852667-1-tujinjiang@huawei.com
> Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes")
> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
> Cc: Andi Kleen <andi@firstfloor.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Cc: Muchun Song <muchun.song@linux.dev>
> Cc: Oscar Salvador <osalvador@suse.de>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
>   mm/hugetlb.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/mm/hugetlb.c~mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages
> +++ a/mm/hugetlb.c
> @@ -3937,7 +3937,7 @@ static int set_max_huge_pages(struct hst
>   	 * and won't grow the pool anywhere else. Not until one of the
>   	 * sysctls are changed, or the surplus pages go out of use.
>   	 */
> -	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
> +	min_count = h->resv_huge_pages + persistent_huge_pages(h) - h->free_huge_pages;
>   	min_count = max(count, min_count);
>   	try_to_free_low(h, min_count, nodes_allowed);
>   
> _
>
> Patches currently in -mm which might be from tujinjiang@huawei.com are
>
> mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order.patch
>

Re: [merged mm-stable] mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch removed from -mm tree

[Andrew Morton]

On Mon, 17 Mar 2025 14:29:03 +0800 Jinjiang Tu <tujinjiang@huawei.com> wrote:

> 
> 在 2025/3/17 13:14, Andrew Morton 写道:
> > The quilt patch titled
> >       Subject: mm/hugetlb: fix set_max_huge_pages() when there are surplus pages
> > has been removed from the -mm tree.  Its filename was
> >       mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch
> >
> > This patch was dropped because it was merged into the mm-stable branch
> > of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> 
> Hi, Andrew
> 
> As I explained in https://lore.kernel.org/all/c2c3d8b5-4b99-220e-20e0-e4a9dd8f5ecf@huawei.com/,
> This patch fails to deal with free surplus huge pages, and will introduce another issue.
> 
> So please drop this patch from mm tree.

OK, thanks, dropped.