Commit 50765b46 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm/mm_init: make memmap_init_compound() look more like prep_compound_page() 

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: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarMike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: default avatarWei Yang <richard.weiyang@gmail.com>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7b4f21f5

mm/mm_init.c

+7 −8
Original line number Diff line number Diff line
@@ -1091,6 +1091,12 @@ static void __ref memmap_init_compound(struct page *head, 
	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(struct page *head, 
		__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,