The patch titled
Subject: mm/hugetlb: fix set_max_huge_pages() when there are surplus pages
has been added to the -mm mm-unstable branch. Its filename is
mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jinjiang Tu <tujinjiang@xxxxxxxxxx>
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 leads to failing
to freeing 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
Link: https://lkml.kernel.org/r/20250225141933.3852667-1-tujinjiang@xxxxxxxxxx
Fixes: 9a30523066cd ("hugetlb: add per node hstate attributes")
Signed-off-by: Jinjiang Tu <tujinjiang@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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
@@ -3933,7 +3933,7 @@ 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@xxxxxxxxxx are
mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch
