[merged mm-stable] mm-mm_init-make-memmap_init_compound-look-more-like-prep_compound_page.patch removed from -mm tree

[merged mm-stable] mm-mm_init-make-memmap_init_compound-look-more-like-prep_compound_page.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/mm_init: make memmap_init_compound() look more like prep_compound_page()
has been removed from the -mm tree.  Its filename was
     mm-mm_init-make-memmap_init_compound-look-more-like-prep_compound_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@redhat.com>
Subject: mm/mm_init: make memmap_init_compound() look more like prep_compound_page()
Date: Mon, 1 Sep 2025 17:03:30 +0200

Grepping for "prep_compound_page" leaves on clueless how devdax gets its
compound pages initialized.

Let's add a comment that might help finding this open-coded
prep_compound_page() initialization more easily.

Further, let's be less smart about the ordering of initialization and just
perform the prep_compound_head() call after all tail pages were
initialized: just like prep_compound_page() does.

No need for a comment to describe the initialization order: again, just
like prep_compound_page().

Link: https://lkml.kernel.org/r/20250901150359.867252-10-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mm_init.c |   15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

--- a/mm/mm_init.c~mm-mm_init-make-memmap_init_compound-look-more-like-prep_compound_page
+++ a/mm/mm_init.c
@@ -1091,6 +1091,12 @@ static void __ref memmap_init_compound(s
 	unsigned long pfn, end_pfn = head_pfn + nr_pages;
 	unsigned int order = pgmap->vmemmap_shift;
 
+	/*
+	 * We have to initialize the pages, including setting up page links.
+	 * prep_compound_page() does not take care of that, so instead we
+	 * open-code prep_compound_page() so we can take care of initializing
+	 * the pages in the same go.
+	 */
 	__SetPageHead(head);
 	for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) {
 		struct page *page = pfn_to_page(pfn);
@@ -1098,15 +1104,8 @@ static void __ref memmap_init_compound(s
 		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
 		prep_compound_tail(head, pfn - head_pfn);
 		set_page_count(page, 0);
-
-		/*
-		 * The first tail page stores important compound page info.
-		 * Call prep_compound_head() after the first tail page has
-		 * been initialized, to not have the data overwritten.
-		 */
-		if (pfn == head_pfn + 1)
-			prep_compound_head(head, order);
 	}
+	prep_compound_head(head, order);
 }
 
 void __ref memmap_init_zone_device(struct zone *zone,
_

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