mm: change the interface of prep_compound_tail()

Instead of passing down the head page and tail page index, pass the tail
and head pages directly, as well as the order of the compound page.

This is a preparation for changing how the head position is encoded in the
tail page.

Link: https://lkml.kernel.org/r/20260227194302.274384-3-kas@kernel.org
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (arm) <david@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Baoquan He <bhe@redhat.com>
Cc: Christoph Lameter <cl@gentwo.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Frank van der Linden <fvdl@google.com>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 415e9f2ef616b5ec6bc1bbf8ef60077e00f3caff..7729a4a28b443d10a7494b1977180f9354af651a 100644 (file)
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -870,9 +870,10 @@ static inline bool folio_test_large(const struct folio *folio)
        return folio_test_head(folio);
 }
 
-static __always_inline void set_compound_head(struct page *page, struct page *head)
+static __always_inline void set_compound_head(struct page *tail,
+               const struct page *head, unsigned int order)
 {
-       WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
+       WRITE_ONCE(tail->compound_head, (unsigned long)head + 1);
 }
 
 static __always_inline void clear_compound_head(struct page *page)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 327eaa4074d394a6e857e03edb0ab5f5771cb6f6..1d41fa3dd43efb2e1ca6a1410f9f8908a581c0b7 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3168,6 +3168,7 @@ found:
 
 /* Initialize [start_page:end_page_number] tail struct pages of a hugepage */
 static void __init hugetlb_folio_init_tail_vmemmap(struct folio *folio,
+                                       struct hstate *h,
                                        unsigned long start_page_number,
                                        unsigned long end_page_number)
 {
@@ -3176,6 +3177,7 @@ static void __init hugetlb_folio_init_tail_vmemmap(struct folio *folio,
        struct page *page = folio_page(folio, start_page_number);
        unsigned long head_pfn = folio_pfn(folio);
        unsigned long pfn, end_pfn = head_pfn + end_page_number;
+       unsigned int order = huge_page_order(h);
 
        /*
         * As we marked all tail pages with memblock_reserved_mark_noinit(),
@@ -3183,7 +3185,7 @@ static void __init hugetlb_folio_init_tail_vmemmap(struct folio *folio,
         */
        for (pfn = head_pfn + start_page_number; pfn < end_pfn; page++, pfn++) {
                __init_single_page(page, pfn, zone, nid);
-               prep_compound_tail((struct page *)folio, pfn - head_pfn);
+               prep_compound_tail(page, &folio->page, order);
                set_page_count(page, 0);
        }
 }
@@ -3203,7 +3205,7 @@ static void __init hugetlb_folio_init_vmemmap(struct folio *folio,
        __folio_set_head(folio);
        ret = folio_ref_freeze(folio, 1);
        VM_BUG_ON(!ret);
-       hugetlb_folio_init_tail_vmemmap(folio, 1, nr_pages);
+       hugetlb_folio_init_tail_vmemmap(folio, h, 1, nr_pages);
        prep_compound_head(&folio->page, huge_page_order(h));
 }
 
@@ -3260,7 +3262,7 @@ static void __init prep_and_add_bootmem_folios(struct hstate *h,
                         * time as this is early in boot and there should
                         * be no contention.
                         */
-                       hugetlb_folio_init_tail_vmemmap(folio,
+                       hugetlb_folio_init_tail_vmemmap(folio, h,
                                        HUGETLB_VMEMMAP_RESERVE_PAGES,
                                        pages_per_huge_page(h));
                }

diff --git a/mm/internal.h b/mm/internal.h
index 2daa6a744172ef47501776db6bf293c352a1844c..9cfbd8e419145f7b8a15e71b0b7f2734a5250502 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -897,13 +897,12 @@ static inline void prep_compound_head(struct page *page, unsigned int order)
                INIT_LIST_HEAD(&folio->_deferred_list);
 }
 
-static inline void prep_compound_tail(struct page *head, int tail_idx)
+static inline void prep_compound_tail(struct page *tail,
+               const struct page *head, unsigned int order)
 {
-       struct page *p = head + tail_idx;
-
-       p->mapping = TAIL_MAPPING;
-       set_compound_head(p, head);
-       set_page_private(p, 0);
+       tail->mapping = TAIL_MAPPING;
+       set_compound_head(tail, head, order);
+       set_page_private(tail, 0);
 }
 
 void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags);

diff --git a/mm/mm_init.c b/mm/mm_init.c
index f903747ca854d04187b31633265139acb29e69d4..5b261f86ba6f3ab5bf4bbb7f164c003a4e907056 100644 (file)
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1110,7 +1110,7 @@ static void __ref memmap_init_compound(struct page *head,
                struct page *page = pfn_to_page(pfn);
 
                __init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
-               prep_compound_tail(head, pfn - head_pfn);
+               prep_compound_tail(page, head, order);
                set_page_count(page, 0);
        }
        prep_compound_head(head, order);

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 74b603872f3468dcb70d77ea98b6a9529c2b29f0..11f9a0525a3a95028ac511a59f717d36c224edff 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -744,7 +744,7 @@ void prep_compound_page(struct page *page, unsigned int order)
 
        __SetPageHead(page);
        for (i = 1; i < nr_pages; i++)
-               prep_compound_tail(page, i);
+               prep_compound_tail(page + i, page, order);
 
        prep_compound_head(page, order);
 }