Commit b06dc281 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm/rmap: introduce folio_remove_rmap_[pte|ptes|pmd]() 

Let's mimic what we did with folio_add_file_rmap_*() and
folio_add_anon_rmap_*() so we can similarly replace page_remove_rmap()
next.

Make the compiler always special-case on the granularity by using
__always_inline.

We're adding folio_remove_rmap_ptes() handling right away, as we want to
use that soon for batching rmap operations when unmapping PTE-mapped large
folios.

Link: https://lkml.kernel.org/r/20231220224504.646757-24-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 0cae959e

include/linux/rmap.h

+6 −0
Original line number Diff line number Diff line
@@ -243,6 +243,12 @@ void folio_add_file_rmap_pmd(struct folio *, struct page *, 
		struct vm_area_struct *);

void page_remove_rmap(struct page *, struct vm_area_struct *,

		bool compound);

void folio_remove_rmap_ptes(struct folio *, struct page *, int nr_pages,

		struct vm_area_struct *);

#define folio_remove_rmap_pte(folio, page, vma) \

	folio_remove_rmap_ptes(folio, page, 1, vma)

void folio_remove_rmap_pmd(struct folio *, struct page *,

		struct vm_area_struct *);



void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *,

		unsigned long address, rmap_t flags);

mm/rmap.c

+66 −16
Original line number Diff line number Diff line
@@ -1510,25 +1510,37 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, 
		bool compound)

{

	struct folio *folio = page_folio(page);



	if (likely(!compound))

		folio_remove_rmap_pte(folio, page, vma);

	else

		folio_remove_rmap_pmd(folio, page, vma);

}



static __always_inline void __folio_remove_rmap(struct folio *folio,

		struct page *page, int nr_pages, struct vm_area_struct *vma,

		enum rmap_level level)

{

	atomic_t *mapped = &folio->_nr_pages_mapped;

	int nr = 0, nr_pmdmapped = 0;

	bool last;

	int last, nr = 0, nr_pmdmapped = 0;

	enum node_stat_item idx;



	VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);

	VM_BUG_ON_PAGE(compound && !PageHead(page), page);

	__folio_rmap_sanity_checks(folio, page, nr_pages, level);



	/* Is page being unmapped by PTE? Is this its last map to be removed? */

	if (likely(!compound)) {

	switch (level) {

	case RMAP_LEVEL_PTE:

		do {

			last = atomic_add_negative(-1, &page->_mapcount);

		nr = last;

			if (last && folio_test_large(folio)) {

			nr = atomic_dec_return_relaxed(mapped);

			nr = (nr < COMPOUND_MAPPED);

				last = atomic_dec_return_relaxed(mapped);

				last = (last < COMPOUND_MAPPED);

			}

	} else if (folio_test_pmd_mappable(folio)) {

		/* That test is redundant: it's for safety or to optimize out */



			if (last)

				nr++;

		} while (page++, --nr_pages > 0);

		break;

	case RMAP_LEVEL_PMD:

		last = atomic_add_negative(-1, &folio->_entire_mapcount);

		if (last) {

			nr = atomic_sub_return_relaxed(COMPOUND_MAPPED, mapped);
@@ -1543,6 +1555,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, 
				nr = 0;

			}

		}

		break;

	}



	if (nr_pmdmapped) {
@@ -1564,7 +1577,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, 
		 * is still mapped.

		 */

		if (folio_test_large(folio) && folio_test_anon(folio))

			if (!compound || nr < nr_pmdmapped)

			if (level == RMAP_LEVEL_PTE || nr < nr_pmdmapped)

				deferred_split_folio(folio);

	}
@@ -1579,6 +1592,43 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, 
	munlock_vma_folio(folio, vma);

}



/**

 * folio_remove_rmap_ptes - remove PTE mappings from a page range of a folio

 * @folio:	The folio to remove the mappings from

 * @page:	The first page to remove

 * @nr_pages:	The number of pages that will be removed from the mapping

 * @vma:	The vm area from which the mappings are removed

 *

 * The page range of the folio is defined by [page, page + nr_pages)

 *

 * The caller needs to hold the page table lock.

 */

void folio_remove_rmap_ptes(struct folio *folio, struct page *page,

		int nr_pages, struct vm_area_struct *vma)

{

	__folio_remove_rmap(folio, page, nr_pages, vma, RMAP_LEVEL_PTE);

}



/**

 * folio_remove_rmap_pmd - remove a PMD mapping from a page range of a folio

 * @folio:	The folio to remove the mapping from

 * @page:	The first page to remove

 * @vma:	The vm area from which the mapping is removed

 *

 * The page range of the folio is defined by [page, page + HPAGE_PMD_NR)

 *

 * The caller needs to hold the page table lock.

 */

void folio_remove_rmap_pmd(struct folio *folio, struct page *page,

		struct vm_area_struct *vma)

{

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	__folio_remove_rmap(folio, page, HPAGE_PMD_NR, vma, RMAP_LEVEL_PMD);

#else

	WARN_ON_ONCE(true);

#endif

}



/*

 * @arg: enum ttu_flags will be passed to this argument

 */