mm: non-pmd-mappable, large folios for folio_add_new_anon_rmap()

In preparation for supporting anonymous multi-size THP, 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/20231207161211.2374093-3-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>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Barry Song <v-songbaohua@oppo.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.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: 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>

diff --git a/mm/rmap.c b/mm/rmap.c
index 49e4d86a4f70120fae8e26e166bb084acb9a5dab..b086dc957b0cba054903db02efb9cbf173897139 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1305,32 +1305,44 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
  * 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);
+       __folio_set_anon(folio, vma, address, true);
 
-       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;
+               SetPageAnonExclusive(&folio->page);
+       } 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);
+                       SetPageAnonExclusive(page);
+               }
+
+               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);
+               SetPageAnonExclusive(&folio->page);
                __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr);
        }
 
        __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
-       __folio_set_anon(folio, vma, address, true);
-       SetPageAnonExclusive(&folio->page);
 }
 
 /**