[PATCH v4 4/4] mm: Add zap_skip_check_mapping() helper
From: Peter Xu <peterx@redhat.com>
Date: 2021-09-15 18:15:47
Also in:
lkml
Subsystem:
memory management, memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
Use the helper for the checks. Rename "check_mapping" into "zap_mapping" because "check_mapping" looks like a bool but in fact it stores the mapping itself. When it's set, we check the mapping (it must be non-NULL). When it's cleared we skip the check, which works like the old way. Move the duplicated comments to the helper too. Reviewed-by: Alistair Popple <apopple@nvidia.com> Signed-off-by: Peter Xu <peterx@redhat.com> --- include/linux/mm.h | 16 +++++++++++++++- mm/memory.c | 29 ++++++----------------------- 2 files changed, 21 insertions(+), 24 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d1126f731221..ed44f31615d9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -1721,10 +1721,24 @@ extern void user_shm_unlock(size_t, struct ucounts *); * Parameter block passed down to zap_pte_range in exceptional cases. */ struct zap_details { - struct address_space *check_mapping; /* Check page->mapping if set */ + struct address_space *zap_mapping; /* Check page->mapping if set */ struct page *single_page; /* Locked page to be unmapped */ }; +/* + * We set details->zap_mappings when we want to unmap shared but keep private + * pages. Return true if skip zapping this page, false otherwise. + */ +static inline bool +zap_skip_check_mapping(struct zap_details *details, struct page *page) +{ + if (!details || !page) + return false; + + return details->zap_mapping && + (details->zap_mapping != page_rmapping(page)); +} + struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte); struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
diff --git a/mm/memory.c b/mm/memory.c
index a7e427177817..8db8ce0ca6ce 100644
--- a/mm/memory.c
+++ b/mm/memory.c@@ -1333,16 +1333,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, struct page *page; page = vm_normal_page(vma, addr, ptent); - if (unlikely(details) && page) { - /* - * unmap_shared_mapping_pages() wants to - * invalidate cache without truncating: - * unmap shared but keep private pages. - */ - if (details->check_mapping && - details->check_mapping != page_rmapping(page)) - continue; - } + if (unlikely(zap_skip_check_mapping(details, page))) + continue; ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); tlb_remove_tlb_entry(tlb, pte, addr);
@@ -1375,17 +1367,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, is_device_exclusive_entry(entry)) { struct page *page = pfn_swap_entry_to_page(entry); - if (unlikely(details && details->check_mapping)) { - /* - * unmap_shared_mapping_pages() wants to - * invalidate cache without truncating: - * unmap shared but keep private pages. - */ - if (details->check_mapping != - page_rmapping(page)) - continue; - } - + if (unlikely(zap_skip_check_mapping(details, page))) + continue; pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); rss[mm_counter(page)]--;
@@ -3369,7 +3352,7 @@ void unmap_mapping_page(struct page *page) first_index = page->index; last_index = page->index + thp_nr_pages(page) - 1; - details.check_mapping = mapping; + details.zap_mapping = mapping; details.single_page = page; i_mmap_lock_write(mapping);
@@ -3398,7 +3381,7 @@ void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, pgoff_t first_index = start; pgoff_t last_index = start + nr - 1; - details.check_mapping = even_cows ? NULL : mapping; + details.zap_mapping = even_cows ? NULL : mapping; if (last_index < first_index) last_index = ULONG_MAX;
--
2.31.1