From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E886CC433B4 for ; Wed, 5 May 2021 13:19:55 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 1AB30613C3 for ; Wed, 5 May 2021 13:19:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1AB30613C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-21245-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 5872 invoked by uid 550); 5 May 2021 13:19:47 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 5840 invoked from network); 5 May 2021 13:19:46 -0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=098DjoJGnAPT9eohEm8f+BcKiqTmmyQ4t8gfr7TicWI=; b=W/WiWgFI7/UtyDk6pyHlsqYp4K tYY8VbPIiaG2BWw5+Vw/D6CqfT8qaPGMRiSsLCW9RhfQIdPcdRbpLGtWXAufrZDubMi/1ZjoU1Cl1 qlEF64APhf9cI9xQJ7mHF64do+531IRURlEmwtEIRT590CGh6fNyOi78tmtxv8zU/Hys5Ve7fEv4U sXaG7AzMeCHPmy3XV3h1yOYGIgvgL8cLVkkWZKxqeyUtXdS4kujL19WYnqA421aSy4AD7xxt3G89S LE/IeGEMKQvnznVqRd72pPp1OJSIELgz6zT8K/HRNelZfqXRikgLOkef6YPUlnlA95kTyqckm7KQ3 rkRg0P+A==; Date: Wed, 5 May 2021 15:19:18 +0200 From: Peter Zijlstra To: Mike Rapoport Cc: Rick Edgecombe , dave.hansen@intel.com, luto@kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, linux-hardening@vger.kernel.org, kernel-hardening@lists.openwall.com, ira.weiny@intel.com, dan.j.williams@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC 5/9] x86, mm: Use cache of page tables Message-ID: References: <20210505003032.489164-1-rick.p.edgecombe@intel.com> <20210505003032.489164-6-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, May 05, 2021 at 03:09:09PM +0300, Mike Rapoport wrote: > On Wed, May 05, 2021 at 10:51:55AM +0200, Peter Zijlstra wrote: > > On Tue, May 04, 2021 at 05:30:28PM -0700, Rick Edgecombe wrote: > > > @@ -54,6 +98,8 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte) > > > { > > > pgtable_pte_page_dtor(pte); > > > paravirt_release_pte(page_to_pfn(pte)); > > > + /* Set Page Table so swap knows how to free it */ > > > + __SetPageTable(pte); > > > paravirt_tlb_remove_table(tlb, pte); > > > } > > > > > > @@ -70,12 +116,16 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd) > > > tlb->need_flush_all = 1; > > > #endif > > > pgtable_pmd_page_dtor(page); > > > + /* Set Page Table so swap nows how to free it */ > > > + __SetPageTable(virt_to_page(pmd)); > > > paravirt_tlb_remove_table(tlb, page); > > > } > > > > > > #if CONFIG_PGTABLE_LEVELS > 3 > > > void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud) > > > { > > > + /* Set Page Table so swap nows how to free it */ > > > + __SetPageTable(virt_to_page(pud)); > > > paravirt_release_pud(__pa(pud) >> PAGE_SHIFT); > > > paravirt_tlb_remove_table(tlb, virt_to_page(pud)); > > > } > > > @@ -83,6 +133,8 @@ void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud) > > > #if CONFIG_PGTABLE_LEVELS > 4 > > > void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d) > > > { > > > + /* Set Page Table so swap nows how to free it */ > > > + __SetPageTable(virt_to_page(p4d)); > > > paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT); > > > paravirt_tlb_remove_table(tlb, virt_to_page(p4d)); > > > } > > > > This, to me, seems like a really weird place to __SetPageTable(), why > > can't we do that on allocation? > > We call __ClearPageTable() at pgtable_pxy_page_dtor(), so at least for pte > and pmd we need to somehow tell release_pages() what kind of page it was. Hurph, right, but then the added comment is misleading; s/Set/Reset/g. Still I'm thinking that if we do these allocators, moving the set/clear to the allocator would be the most natural place, perhaps we can remove them from the {c,d}tor.