Commit 5b4bd90f authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

rmap: add folio parameter to __page_set_anon_rmap() 

Avoid the compound_head() call in PageAnon() by passing in the folio that
all callers have.  Also save me from wondering whether page->mapping can
ever be overwritten on a tail page (I don't think it can, but I'm not 100%
sure).

Link: https://lkml.kernel.org/r/20230116192959.2147032-1-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent e0650a41

mm/rmap.c

+11 −10
Original line number Diff line number Diff line
@@ -1131,19 +1131,20 @@ void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma) 


/**

 * __page_set_anon_rmap - set up new anonymous rmap

 * @page:	Page or Hugepage to add to rmap

 * @folio:	Folio which contains page.

 * @page:	Page to add to rmap.

 * @vma:	VM area to add page to.

 * @address:	User virtual address of the mapping	

 * @exclusive:	the page is exclusively owned by the current process

 */

static void __page_set_anon_rmap(struct page *page,

static void __page_set_anon_rmap(struct folio *folio, struct page *page,

	struct vm_area_struct *vma, unsigned long address, int exclusive)

{

	struct anon_vma *anon_vma = vma->anon_vma;



	BUG_ON(!anon_vma);



	if (PageAnon(page))

	if (folio_test_anon(folio))

		goto out;



	/*
@@ -1155,14 +1156,14 @@ static void __page_set_anon_rmap(struct page *page, 
		anon_vma = anon_vma->root;



	/*

	 * page_idle does a lockless/optimistic rmap scan on page->mapping.

	 * page_idle does a lockless/optimistic rmap scan on folio->mapping.

	 * Make sure the compiler doesn't split the stores of anon_vma and

	 * the PAGE_MAPPING_ANON type identifier, otherwise the rmap code

	 * could mistake the mapping for a struct address_space and crash.

	 */

	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;

	WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);

	page->index = linear_page_index(vma, address);

	WRITE_ONCE(folio->mapping, (struct address_space *) anon_vma);

	folio->index = linear_page_index(vma, address);

out:

	if (exclusive)

		SetPageAnonExclusive(page);
@@ -1254,7 +1255,7 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, 
	if (likely(!folio_test_ksm(folio))) {

		/* address might be in next vma when migration races vma_adjust */

		if (first)

			__page_set_anon_rmap(page, vma, address,

			__page_set_anon_rmap(folio, page, vma, address,

					     !!(flags & RMAP_EXCLUSIVE));

		else

			__page_check_anon_rmap(page, vma, address);
@@ -1297,7 +1298,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, 
	}



	__lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);

	__page_set_anon_rmap(&folio->page, vma, address, 1);

	__page_set_anon_rmap(folio, &folio->page, vma, address, 1);

}



/**
@@ -2528,7 +2529,7 @@ void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma, 
	VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page);

	VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);

	if (first)

		__page_set_anon_rmap(page, vma, address,

		__page_set_anon_rmap(folio, page, vma, address,

				     !!(flags & RMAP_EXCLUSIVE));

}
@@ -2541,6 +2542,6 @@ void hugepage_add_new_anon_rmap(struct page *page, 
	/* increment count (starts at -1) */

	atomic_set(&folio->_entire_mapcount, 0);

	folio_clear_hugetlb_restore_reserve(folio);

	__page_set_anon_rmap(page, vma, address, 1);

	__page_set_anon_rmap(folio, page, vma, address, 1);

}

#endif /* CONFIG_HUGETLB_PAGE */