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=-11.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 C2BC1C4360C for ; Wed, 5 May 2021 12:14:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A3AF361185 for ; Wed, 5 May 2021 12:14:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233911AbhEEMOU (ORCPT ); Wed, 5 May 2021 08:14:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:51578 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231828AbhEEMKO (ORCPT ); Wed, 5 May 2021 08:10:14 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 72AB4613EC; Wed, 5 May 2021 12:09:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620216557; bh=eyDndtMwyuRmZym1pTFZiZuIz6uTY2r81jIr1/YiEfg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=U7fttDsTmI9wiuK7swO0Hm9SCpKEYoFuamTqMfTz7sbh91z3OeazDwC35vIS1g+9u A1MnTY4490ECSNp7bClvXAoEPK+UOd25mM2GL4tfok4OlG50SHKaoefpJhejSUeTDQ 5Pzk2ttsInuAGZrgxToTAaF9aduPpi2k2nz/toKqNUKAEoTHnxmtGob1eoKJoK/lRP xbdj7bMrHguSWDTw/HoQMwJhMPK0mT8CqmlOYzB0NVjuweRbBUrnvkwqpg+rmTtlXV hRQVvDRxErrL1C0dDOS+mLPoipijqB7jHDnWfzUWIbhuCX4yidlh9uI6JiZfv9yL3B q7GQAR9yK3YDA== Date: Wed, 5 May 2021 15:09:09 +0300 From: Mike Rapoport To: Peter Zijlstra 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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > > @@ -888,6 +889,12 @@ void release_pages(struct page **pages, int nr) > > continue; > > } > > > > + if (PageTable(page)) { > > + __ClearPageTable(page); > > + free_table(page); > > + continue; > > + } > > + > > if (!put_page_testzero(page)) > > continue; > > > > diff --git a/mm/swap_state.c b/mm/swap_state.c > > index 3cdee7b11da9..a60ec3d4ab21 100644 > > --- a/mm/swap_state.c > > +++ b/mm/swap_state.c > > @@ -22,6 +22,7 @@ > > #include > > #include > > #include > > +#include > > #include "internal.h" > > > > /* > > @@ -310,6 +311,11 @@ static inline void free_swap_cache(struct page *page) > > void free_page_and_swap_cache(struct page *page) > > { > > free_swap_cache(page); > > + if (PageTable(page)) { > > + __ClearPageTable(page); > > + free_table(page); > > + return; > > + } > > if (!is_huge_zero_page(page)) > > put_page(page); > > } > > And then free_table() can __ClearPageTable() and all is nice and > symmetric and all this weirdness goes away, no? -- Sincerely yours, Mike.