Commit 184e916c authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm/ksm: convert get_mergeable_page() from follow_page() to folio_walk 

Let's use folio_walk instead, for example avoiding taking temporary folio
references if the folio does not even apply and getting rid of one more
follow_page() user.

Note that zeropages obviously don't apply: old code could just have
specified FOLL_DUMP.  Anon folios are never secretmem, so we don't care
about losing the check in follow_page().

Link: https://lkml.kernel.org/r/20240802155524.517137-6-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7dff875c

mm/ksm.c

+14 −12
Original line number Diff line number Diff line
@@ -767,26 +767,28 @@ static struct page *get_mergeable_page(struct ksm_rmap_item *rmap_item) 
	struct mm_struct *mm = rmap_item->mm;

	unsigned long addr = rmap_item->address;

	struct vm_area_struct *vma;

	struct page *page;

	struct page *page = NULL;

	struct folio_walk fw;

	struct folio *folio;



	mmap_read_lock(mm);

	vma = find_mergeable_vma(mm, addr);

	if (!vma)

		goto out;



	page = follow_page(vma, addr, FOLL_GET);

	if (IS_ERR_OR_NULL(page))

		goto out;

	if (is_zone_device_page(page))

		goto out_putpage;

	if (PageAnon(page)) {

	folio = folio_walk_start(&fw, vma, addr, 0);

	if (folio) {

		if (!folio_is_zone_device(folio) &&

		    folio_test_anon(folio)) {

			folio_get(folio);

			page = fw.page;

		}

		folio_walk_end(&fw, vma);

	}

out:

	if (page) {

		flush_anon_page(vma, page, addr);

		flush_dcache_page(page);

	} else {

out_putpage:

		put_page(page);

out:

		page = NULL;

	}

	mmap_read_unlock(mm);

	return page;