Commit 91b61ef3 authored by Peter Xu's avatar Peter Xu Committed by Linus Torvalds
Browse files

mm: add zap_skip_check_mapping() helper 

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.

Link: https://lkml.kernel.org/r/20210915181538.11288-1-peterx@redhat.com


Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Reviewed-by: default avatarAlistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 232a6a1c

include/linux/mm.h

+15 −1
Original line number Diff line number Diff line
@@ -1687,10 +1687,24 @@ 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,

mm/memory.c

+6 −23
Original line number Diff line number Diff line
@@ -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))

			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))

			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;