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[174.91.135.175]) by smtp.gmail.com with ESMTPSA id n6sm5031793qtx.22.2021.03.22.17.49.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Mar 2021 17:49:25 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: "Kirill A . Shutemov" , Jerome Glisse , Mike Kravetz , Matthew Wilcox , Andrew Morton , Axel Rasmussen , Hugh Dickins , peterx@redhat.com, Nadav Amit , Andrea Arcangeli , Mike Rapoport Subject: [PATCH 07/23] mm: Introduce zap_details.zap_flags Date: Mon, 22 Mar 2021 20:48:56 -0400 Message-Id: <20210323004912.35132-8-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210323004912.35132-1-peterx@redhat.com> References: <20210323004912.35132-1-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-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 80E4EA0000FC X-Stat-Signature: 7qsrpkjzfb7kza44ga47gejbmuonuyg9 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf23; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=170.10.133.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616460569-326650 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 389dd91134f9..bb513a346beb 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1702,13 +1702,30 @@ 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 5e6175e00617..2e540b315481 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1242,16 +1242,8 @@ 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); @@ -1283,17 +1275,8 @@ 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); @@ -3242,9 +3225,11 @@ 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;