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Shutemov" , Andrew Morton Subject: [PATCH 2/3] mm: Introduce zap_details.zap_flags Date: Mon, 7 Dec 2020 21:50:21 -0500 Message-Id: <20201208025022.8234-3-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201208025022.8234-1-peterx@redhat.com> References: <20201208025022.8234-1-peterx@redhat.com> MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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: Instead of trying to introduce one variable for every new zap_details fields, let's introduce a flag so that it can start to encode true/false informations. Let's start to use this flag first to clean up the only check_mapping variable. Firstly, the name "check_mapping" implies this is a "boolean", but actually it stores the mapping inside, just in a way that it won't be set if we don't want to check the mapping. To make things clearer, introduce the 1st zap flag ZAP_FLAG_CHECK_MAPPING, so that we only check against the mapping if this bit set. At the same time, we can rename check_mapping into zap_mapping and set it always. Since at it, introduce another helper zap_check_mapping_skip() and use it in zap_pte_range() properly. Some old comments have been removed in zap_pte_range() because they're duplicated, and since now we're with ZAP_FLAG_CHECK_MAPPING flag, it'll be very easy to grep this information by simply grepping the flag. It'll also make life easier when we want to e.g. pass in zap_flags into the callers like unmap_mapping_pages() (instead of adding new booleans besides the even_cows parameter). Signed-off-by: Peter Xu --- include/linux/mm.h | 19 ++++++++++++++++++- mm/memory.c | 31 ++++++++----------------------- 2 files changed, 26 insertions(+), 24 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 5d977e484095..7ed4352ec84f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1620,13 +1620,30 @@ static inline bool can_do_mlock(void) { return false; } extern int user_shm_lock(size_t, struct user_struct *); extern void user_shm_unlock(size_t, struct user_struct *); +/* Whether to check page->mapping when zapping */ +#define ZAP_FLAG_CHECK_MAPPING BIT(0) + /* * 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 */ + unsigned long zap_flags; /* Special flags for zapping */ }; +/* Return true if skip zapping this page, false otherwise */ +static inline bool +zap_check_mapping_skip(struct zap_details *details, struct page *page) +{ + if (!details || !page) + return false; + + if (!(details->zap_flags & ZAP_FLAG_CHECK_MAPPING)) + return false; + + return 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 70d57c39380d..20a8ba05c334 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1220,16 +1220,8 @@ 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_check_mapping_skip(details, page))) + continue; ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); tlb_remove_tlb_entry(tlb, pte, addr); @@ -1261,17 +1253,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, if (is_device_private_entry(entry)) { struct page *page = device_private_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_check_mapping_skip(details, page))) + continue; pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); rss[mm_counter(page)]--; page_remove_rmap(page, false); @@ -3176,9 +3159,11 @@ void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, pgoff_t nr, bool even_cows) { pgoff_t first_index = start, last_index = start + nr - 1; - struct zap_details details = { }; + struct zap_details details = { .zap_mapping = mapping }; + + if (!even_cows) + details.zap_flags |= ZAP_FLAG_CHECK_MAPPING; - details.check_mapping = even_cows ? NULL : mapping; if (last_index < first_index) last_index = ULONG_MAX;