diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 36 |
1 files changed, 8 insertions, 28 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b26998d1845f..7703169107c6 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2142,6 +2142,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, VM_BUG_ON_PAGE(!page_count(page), page); page_ref_add(page, HPAGE_PMD_NR - 1); + atomic_add(HPAGE_PMD_NR, subpages_mapcount_ptr(page)); /* * Without "freeze", we'll simply split the PMD, propagating the @@ -2225,33 +2226,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pte_unmap(pte); } - if (!pmd_migration) { - /* - * Set PG_double_map before dropping compound_mapcount to avoid - * false-negative page_mapped(). - */ - if (compound_mapcount(page) > 1 && - !TestSetPageDoubleMap(page)) { - for (i = 0; i < HPAGE_PMD_NR; i++) - atomic_inc(&page[i]._mapcount); - } - - lock_page_memcg(page); - if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { - /* Last compound_mapcount is gone. */ - __mod_lruvec_page_state(page, NR_ANON_THPS, - -HPAGE_PMD_NR); - if (TestClearPageDoubleMap(page)) { - /* No need in mapcount reference anymore */ - for (i = 0; i < HPAGE_PMD_NR; i++) - atomic_dec(&page[i]._mapcount); - } - } - unlock_page_memcg(page); - - /* Above is effectively page_remove_rmap(page, vma, true) */ - munlock_vma_page(page, vma, true); - } + if (!pmd_migration) + page_remove_rmap(page, vma, true); smp_wmb(); /* make pte visible before pmd */ pmd_populate(mm, pmd, pgtable); @@ -2453,7 +2429,7 @@ static void __split_huge_page_tail(struct page *head, int tail, (1L << PG_dirty) | LRU_GEN_MASK | LRU_REFS_MASK)); - /* ->mapping in first tail page is compound_mapcount */ + /* ->mapping in first and second tail page is replaced by other uses */ VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, page_tail); page_tail->mapping = head->mapping; @@ -2463,6 +2439,10 @@ static void __split_huge_page_tail(struct page *head, int tail, * page->private should not be set in tail pages with the exception * of swap cache pages that store the swp_entry_t in tail pages. * Fix up and warn once if private is unexpectedly set. + * + * What of 32-bit systems, on which head[1].compound_pincount overlays + * head[1].private? No problem: THP_SWAP is not enabled on 32-bit, and + * compound_pincount must be 0 for folio_ref_freeze() to have succeeded. */ if (!folio_test_swapcache(page_folio(head))) { VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail); |