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mm: add zap_skip_check_mapping() helper

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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: Peter Xu <peterx@redhat.com>
Reviewed-by: Alistair 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Xu 2021-11-05 13:38:34 -07:00 committed by Linus Torvalds
parent 232a6a1c06
commit 91b61ef333
2 changed files with 21 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
include/linux/mm.h
View File

@ -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,

29
mm/memory.c
View File

@ -1333,16 +1333,8 @@ again:
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 @@ again:
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;