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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 CB534C388F7 for ; Mon, 9 Nov 2020 16:48:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7702020789 for ; Mon, 9 Nov 2020 16:48:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="2PklhGFO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730702AbgKIQsH (ORCPT ); Mon, 9 Nov 2020 11:48:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:54586 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730419AbgKIQsH (ORCPT ); Mon, 9 Nov 2020 11:48:07 -0500 Received: from kernel.org (unknown [77.125.7.142]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7C3EA2074F; Mon, 9 Nov 2020 16:47:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604940486; bh=6rn/Is9/mb71Cx8T5OixcswhdKR8Yw8hRoo0YqfjdsY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=2PklhGFO1GSLbrkd4w7eR0OQVXIC9bB/NRFuu0yXJ2cad3g2XWFGm5qY1CfZsxWEJ hIEGvV7DG50YSNEMxKxpw57WvEfw0aU7JllVonG+2csYY0gr4DIxzUIPf5drKxbhRb AQb1wGfM13MfcFzy1XYj4m6UEF/itQaci+zuEFqA= Date: Mon, 9 Nov 2020 18:47:52 +0200 From: Mike Rapoport To: Andrew Morton Cc: Albert Ou , Andy Lutomirski , Benjamin Herrenschmidt , Borislav Petkov , Catalin Marinas , Christian Borntraeger , Christoph Lameter , "David S. Miller" , Dave Hansen , David Hildenbrand , David Rientjes , "Edgecombe, Rick P" , "H. Peter Anvin" , Heiko Carstens , Ingo Molnar , Joonsoo Kim , "Kirill A . Shutemov" , "Kirill A. Shutemov" , Len Brown , Michael Ellerman , Mike Rapoport , Palmer Dabbelt , Paul Mackerras , Paul Walmsley , Pavel Machek , Pekka Enberg , Peter Zijlstra , "Rafael J. Wysocki" , Thomas Gleixner , Vasily Gorbik , Vlastimil Babka , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pm@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v6 0/4] arch, mm: improve robustness of direct map manipulation Message-ID: <20201109164752.GF301837@kernel.org> References: <20201109162415.13764-1-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201109162415.13764-1-rppt@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Oops, this one has some rebase errors, I'll send v7 soon. Sorry for the noise. On Mon, Nov 09, 2020 at 06:24:11PM +0200, Mike Rapoport wrote: > From: Mike Rapoport > > Hi, > > During recent discussion about KVM protected memory, David raised a concern > about usage of __kernel_map_pages() outside of DEBUG_PAGEALLOC scope [1]. > > Indeed, for architectures that define CONFIG_ARCH_HAS_SET_DIRECT_MAP it is > possible that __kernel_map_pages() would fail, but since this function is > void, the failure will go unnoticed. > > Moreover, there's lack of consistency of __kernel_map_pages() semantics > across architectures as some guard this function with > #ifdef DEBUG_PAGEALLOC, some refuse to update the direct map if page > allocation debugging is disabled at run time and some allow modifying the > direct map regardless of DEBUG_PAGEALLOC settings. > > This set straightens this out by restoring dependency of > __kernel_map_pages() on DEBUG_PAGEALLOC and updating the call sites > accordingly. > > Since currently the only user of __kernel_map_pages() outside > DEBUG_PAGEALLOC is hibernation, it is updated to make direct map accesses > there more explicit. > > [1] https://lore.kernel.org/lkml/2759b4bf-e1e3-d006-7d86-78a40348269d@redhat.com > > v6 changes: > * revert slab changes to avoid redundant check of static key > > v5 changes: > * use pairs of _map()/_unmap() functions instead of _map(..., int enable) as > Vlastimil suggested > https://lore.kernel.org/lkml/20201108065758.1815-1-rppt@kernel.org > > v4 changes: > * s/WARN_ON/pr_warn_once/ per David and Kirill > * rebase on v5.10-rc2 > * add Acked/Reviewed tags > https://lore.kernel.org/lkml/20201103162057.22916-1-rppt@kernel.org > > v3 changes: > * update arm64 changes to avoid regression, per Rick's comments > * fix bisectability > https://lore.kernel.org/lkml/20201101170815.9795-1-rppt@kernel.org > > v2 changes: > * Rephrase patch 2 changelog to better describe the change intentions and > implications > * Move removal of kernel_map_pages() from patch 1 to patch 2, per David > https://lore.kernel.org/lkml/20201029161902.19272-1-rppt@kernel.org > > v1: > https://lore.kernel.org/lkml/20201025101555.3057-1-rppt@kernel.org > > Mike Rapoport (4): > mm: introduce debug_pagealloc_{map,unmap}_pages() helpers > PM: hibernate: make direct map manipulations more explicit > arch, mm: restore dependency of __kernel_map_pages() on DEBUG_PAGEALLOC > arch, mm: make kernel_page_present() always available > > arch/Kconfig | 3 +++ > arch/arm64/Kconfig | 4 +-- > arch/arm64/include/asm/cacheflush.h | 1 + > arch/arm64/mm/pageattr.c | 6 +++-- > arch/powerpc/Kconfig | 5 +--- > arch/riscv/Kconfig | 4 +-- > arch/riscv/include/asm/pgtable.h | 2 -- > arch/riscv/include/asm/set_memory.h | 1 + > arch/riscv/mm/pageattr.c | 31 ++++++++++++++++++++++ > arch/s390/Kconfig | 4 +-- > arch/sparc/Kconfig | 4 +-- > arch/x86/Kconfig | 4 +-- > arch/x86/include/asm/set_memory.h | 1 + > arch/x86/mm/pat/set_memory.c | 4 +-- > include/linux/mm.h | 40 ++++++++++++++--------------- > include/linux/set_memory.h | 5 ++++ > kernel/power/snapshot.c | 38 +++++++++++++++++++++++++-- > mm/memory_hotplug.c | 3 +-- > mm/page_alloc.c | 6 ++--- > 19 files changed, 113 insertions(+), 53 deletions(-) > > -- > 2.28.0 > -- Sincerely yours, Mike.