[merged mm-stable] mm-hugetlb-check-for-unreasonable-folio-sizes-when-registering-hstate.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: mm/hugetlb: check for unreasonable folio sizes when registering hstate
has been removed from the -mm tree.  Its filename was
     mm-hugetlb-check-for-unreasonable-folio-sizes-when-registering-hstate.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: David Hildenbrand <david@redhat.com>
Subject: mm/hugetlb: check for unreasonable folio sizes when registering hstate
Date: Mon, 1 Sep 2025 17:03:29 +0200

Let's check that no hstate that corresponds to an unreasonable folio size
is registered by an architecture.  If we were to succeed registering, we
could later try allocating an unsupported gigantic folio size.

Further, let's add a BUILD_BUG_ON() for checking that HUGETLB_PAGE_ORDER
is sane at build time.  As HUGETLB_PAGE_ORDER is dynamic on powerpc, we
have to use a BUILD_BUG_ON_INVALID() to make it compile.

No existing kernel configuration should be able to trigger this check:
either SPARSEMEM without SPARSEMEM_VMEMMAP cannot be configured or
gigantic folios will not exceed a memory section (the case on sparse).

Link: https://lkml.kernel.org/r/20250901150359.867252-9-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/hugetlb.c~mm-hugetlb-check-for-unreasonable-folio-sizes-when-registering-hstate
+++ a/mm/hugetlb.c
@@ -4657,6 +4657,7 @@ static int __init hugetlb_init(void)
 
 	BUILD_BUG_ON(sizeof_field(struct page, private) * BITS_PER_BYTE <
 			__NR_HPAGEFLAGS);
+	BUILD_BUG_ON_INVALID(HUGETLB_PAGE_ORDER > MAX_FOLIO_ORDER);
 
 	if (!hugepages_supported()) {
 		if (hugetlb_max_hstate || default_hstate_max_huge_pages)
@@ -4740,6 +4741,7 @@ void __init hugetlb_add_hstate(unsigned
 	}
 	BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
 	BUG_ON(order < order_base_2(__NR_USED_SUBPAGE));
+	WARN_ON(order > MAX_FOLIO_ORDER);
 	h = &hstates[hugetlb_max_hstate++];
 	__mutex_init(&h->resize_lock, "resize mutex", &h->resize_key);
 	h->order = order;
_

Patches currently in -mm which might be from david@redhat.com are