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Shutemov" , Jerome Glisse , Miaohe Lin , Andrea Arcangeli Subject: [PATCH v4 4/4] mm: Add zap_skip_check_mapping() helper Date: Wed, 15 Sep 2021 14:15:38 -0400 Message-Id: <20210915181538.11288-1-peterx@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210915181456.10739-1-peterx@redhat.com> References: <20210915181456.10739-1-peterx@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=djmRIoDE; spf=none (imf27.hostedemail.com: domain of peterx@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Stat-Signature: ai19oobrdrceujyndwa48kba6k5t8mbu X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7236B70000A7 X-HE-Tag: 1631729742-791755 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 Signed-off-by: Peter Xu --- 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;