+ mm-non-pmd-mappable-large-folios-for-folio_add_new_anon_rmap.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: non-pmd-mappable, large folios for folio_add_new_anon_rmap()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-non-pmd-mappable-large-folios-for-folio_add_new_anon_rmap.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-non-pmd-mappable-large-folios-for-folio_add_new_anon_rmap.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Ryan Roberts <ryan.roberts@arm.com>
Subject: mm: non-pmd-mappable, large folios for folio_add_new_anon_rmap()
Date: Fri, 29 Sep 2023 12:44:13 +0100

In preparation for anonymous large folio support, improve
folio_add_new_anon_rmap() to allow a non-pmd-mappable, large folio to be
passed to it.  In this case, all contained pages are accounted using the
order-0 folio (or base page) scheme.

Link: https://lkml.kernel.org/r/20230929114421.3761121-3-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Itaru Kitayama <itaru.kitayama@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/rmap.c |   26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

--- a/mm/rmap.c~mm-non-pmd-mappable-large-folios-for-folio_add_new_anon_rmap
+++ a/mm/rmap.c
@@ -1321,26 +1321,40 @@ void page_add_anon_rmap(struct page *pag
  * This means the inc-and-test can be bypassed.
  * The folio does not have to be locked.
  *
- * If the folio is large, it is accounted as a THP.  As the folio
+ * If the folio is pmd-mappable, it is accounted as a THP.  As the folio
  * is new, it's assumed to be mapped exclusively by a single process.
  */
 void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 		unsigned long address)
 {
-	int nr;
+	int nr = folio_nr_pages(folio);
 
-	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+	VM_BUG_ON_VMA(address < vma->vm_start ||
+			address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
 	__folio_set_swapbacked(folio);
 
-	if (likely(!folio_test_pmd_mappable(folio))) {
+	if (likely(!folio_test_large(folio))) {
 		/* increment count (starts at -1) */
 		atomic_set(&folio->_mapcount, 0);
-		nr = 1;
+		__page_set_anon_rmap(folio, &folio->page, vma, address, 1);
+	} else if (!folio_test_pmd_mappable(folio)) {
+		int i;
+
+		for (i = 0; i < nr; i++) {
+			struct page *page = folio_page(folio, i);
+
+			/* increment count (starts at -1) */
+			atomic_set(&page->_mapcount, 0);
+			__page_set_anon_rmap(folio, page, vma,
+					address + (i << PAGE_SHIFT), 1);
+		}
+
+		atomic_set(&folio->_nr_pages_mapped, nr);
 	} else {
 		/* increment count (starts at -1) */
 		atomic_set(&folio->_entire_mapcount, 0);
 		atomic_set(&folio->_nr_pages_mapped, COMPOUND_MAPPED);
-		nr = folio_nr_pages(folio);
+		__page_set_anon_rmap(folio, &folio->page, vma, address, 1);
 		__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr);
 	}
 
_

Patches currently in -mm which might be from ryan.roberts@arm.com are

mm-hugetlb-add-huge-page-size-param-to-set_huge_pte_at.patch
arm64-hugetlb-fix-set_huge_pte_at-to-work-with-all-swap-entries.patch
mm-allow-deferred-splitting-of-arbitrary-anon-large-folios.patch
mm-non-pmd-mappable-large-folios-for-folio_add_new_anon_rmap.patch
mm-thp-account-pte-mapped-anonymous-thp-usage.patch
mm-thp-introduce-anon_orders-and-anon_always_mask-sysfs-files.patch
mm-thp-extend-thp-to-allocate-anonymous-large-folios.patch
mm-thp-add-recommend-option-for-anon_orders.patch
arm64-mm-override-arch_wants_pte_order.patch
selftests-mm-cow-generalize-do_run_with_thp-helper.patch
selftests-mm-cow-add-tests-for-small-order-anon-thp.patch