The quilt patch titled
Subject: mm: move hugetlb specific things in folio to page[3]
has been removed from the -mm tree. Its filename was
mm-move-hugetlb-specific-things-in-folio-to-page.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@xxxxxxxxxx>
Subject: mm: move hugetlb specific things in folio to page[3]
Date: Mon, 3 Mar 2025 17:29:57 +0100
Let's just move the hugetlb specific stuff to a separate page, and stop
letting it overlay other fields for now.
This frees up some space in page[2], which we will use on 32bit to free up
some space in page[1]. While we could move these things to page[3]
instead, it's cleaner to just move the hugetlb specific things out of the
way and pack the core-folio stuff as tight as possible. ... and we can
minimize the work required in dump_folio.
We can now avoid re-initializing &folio->_deferred_list in hugetlb code.
Hopefully dynamically allocating "strut folio" in the future will further
clean this up.
Link: https://lkml.kernel.org/r/20250303163014.1128035-5-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Andy Lutomirks^H^Hski <luto@xxxxxxxxxx>
Cc: Borislav Betkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Liam Howlett <liam.howlett@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Matthew Wilcow (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Michal Koutn <mkoutny@xxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: tejun heo <tj@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Zefan Li <lizefan.x@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 27 +++++++++++++++++----------
mm/hugetlb.c | 1 -
mm/page_alloc.c | 5 +++++
3 files changed, 22 insertions(+), 11 deletions(-)
--- a/include/linux/mm_types.h~mm-move-hugetlb-specific-things-in-folio-to-page
+++ a/include/linux/mm_types.h
@@ -407,20 +407,23 @@ struct folio {
unsigned long _flags_2;
unsigned long _head_2;
/* public: */
- void *_hugetlb_subpool;
- void *_hugetlb_cgroup;
- void *_hugetlb_cgroup_rsvd;
- void *_hugetlb_hwpoison;
+ struct list_head _deferred_list;
/* private: the union with struct page is transitional */
};
+ struct page __page_2;
+ };
+ union {
struct {
- unsigned long _flags_2a;
- unsigned long _head_2a;
+ unsigned long _flags_3;
+ unsigned long _head_3;
/* public: */
- struct list_head _deferred_list;
+ void *_hugetlb_subpool;
+ void *_hugetlb_cgroup;
+ void *_hugetlb_cgroup_rsvd;
+ void *_hugetlb_hwpoison;
/* private: the union with struct page is transitional */
};
- struct page __page_2;
+ struct page __page_3;
};
};
@@ -457,8 +460,12 @@ FOLIO_MATCH(_refcount, _refcount_1);
offsetof(struct page, pg) + 2 * sizeof(struct page))
FOLIO_MATCH(flags, _flags_2);
FOLIO_MATCH(compound_head, _head_2);
-FOLIO_MATCH(flags, _flags_2a);
-FOLIO_MATCH(compound_head, _head_2a);
+#undef FOLIO_MATCH
+#define FOLIO_MATCH(pg, fl) \
+ static_assert(offsetof(struct folio, fl) == \
+ offsetof(struct page, pg) + 3 * sizeof(struct page))
+FOLIO_MATCH(flags, _flags_3);
+FOLIO_MATCH(compound_head, _head_3);
#undef FOLIO_MATCH
/**
--- a/mm/hugetlb.c~mm-move-hugetlb-specific-things-in-folio-to-page
+++ a/mm/hugetlb.c
@@ -1649,7 +1649,6 @@ static void __update_and_free_hugetlb_fo
folio_ref_unfreeze(folio, 1);
- INIT_LIST_HEAD(&folio->_deferred_list);
hugetlb_free_folio(folio);
}
--- a/mm/page_alloc.c~mm-move-hugetlb-specific-things-in-folio-to-page
+++ a/mm/page_alloc.c
@@ -971,6 +971,11 @@ static int free_tail_page_prepare(struct
goto out;
}
break;
+ case 3:
+ /* the third tail page: hugetlb specifics overlap ->mappings */
+ if (IS_ENABLED(CONFIG_HUGETLB_PAGE))
+ break;
+ fallthrough;
default:
if (page->mapping != TAIL_MAPPING) {
bad_page(page, "corrupted mapping in tail page");
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
