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=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 A9F9BC00A89 for ; Thu, 5 Nov 2020 11:56:34 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BE6B92065D for ; Thu, 5 Nov 2020 11:56:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="HHJruZEG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BE6B92065D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4CRhnT5SFpzDqJf for ; Thu, 5 Nov 2020 22:56:29 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=rppt@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=default header.b=HHJruZEG; dkim-atps=neutral Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4CRhTK1fBmzDqv5 for ; Thu, 5 Nov 2020 22:42:28 +1100 (AEDT) Received: from kernel.org (unknown [2.55.183.164]) (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 2AF252071A; Thu, 5 Nov 2020 11:42:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604576542; bh=wBBJASevkpsRXZMXJL2OiMK6CtZhq8iWhEgufgr/S4E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HHJruZEGepbkqow1qhwuCKDkVoe/lpKxogvFghtL/5RowA6qyrxSq531Gliqcbzyu tDTgfPvrJ9vN7jvSKObEIq9kiRh1xeaKbxhp+zX6zw46ZOu6eW7fSqiBEMlywA8zjt Ph/W2QEvA7Z47iM8NgnnYxvGybdML21CtLacZNig= Date: Thu, 5 Nov 2020 13:42:00 +0200 From: Mike Rapoport To: Vlastimil Babka Subject: Re: [PATCH v4 3/4] arch, mm: restore dependency of __kernel_map_pages() of DEBUG_PAGEALLOC Message-ID: <20201105114200.GZ4879@kernel.org> References: <20201103162057.22916-1-rppt@kernel.org> <20201103162057.22916-4-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Hildenbrand , Peter Zijlstra , Dave Hansen , linux-mm@kvack.org, Paul Mackerras , Pavel Machek , "H. Peter Anvin" , sparclinux@vger.kernel.org, Christoph Lameter , Will Deacon , linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, x86@kernel.org, Mike Rapoport , Christian Borntraeger , Ingo Molnar , Catalin Marinas , Len Brown , Albert Ou , Vasily Gorbik , linux-pm@vger.kernel.org, Heiko Carstens , David Rientjes , Borislav Petkov , Andy Lutomirski , Paul Walmsley , "Kirill A. Shutemov" , Thomas Gleixner , Joonsoo Kim , linux-arm-kernel@lists.infradead.org, "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Pekka Enberg , Palmer Dabbelt , Andrew Morton , "Edgecombe, Rick P" , linuxppc-dev@lists.ozlabs.org, "David S. Miller" , "Kirill A . Shutemov" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Nov 04, 2020 at 07:02:20PM +0100, Vlastimil Babka wrote: > On 11/3/20 5:20 PM, Mike Rapoport wrote: > > From: Mike Rapoport > > Subject should have "on DEBUG_PAGEALLOC" ? > > > The design of DEBUG_PAGEALLOC presumes that __kernel_map_pages() must never > > fail. With this assumption is wouldn't be safe to allow general usage of > > this function. > > > > Moreover, some architectures that implement __kernel_map_pages() have this > > function guarded by #ifdef DEBUG_PAGEALLOC and some refuse to map/unmap > > pages when page allocation debugging is disabled at runtime. > > > > As all the users of __kernel_map_pages() were converted to use > > debug_pagealloc_map_pages() it is safe to make it available only when > > DEBUG_PAGEALLOC is set. > > > > Signed-off-by: Mike Rapoport > > Acked-by: David Hildenbrand > > Acked-by: Kirill A. Shutemov > > --- > > arch/Kconfig | 3 +++ > > arch/arm64/Kconfig | 4 +--- > > arch/arm64/mm/pageattr.c | 8 ++++++-- > > arch/powerpc/Kconfig | 5 +---- > > arch/riscv/Kconfig | 4 +--- > > arch/riscv/include/asm/pgtable.h | 2 -- > > arch/riscv/mm/pageattr.c | 2 ++ > > arch/s390/Kconfig | 4 +--- > > arch/sparc/Kconfig | 4 +--- > > arch/x86/Kconfig | 4 +--- > > arch/x86/mm/pat/set_memory.c | 2 ++ > > include/linux/mm.h | 10 +++++++--- > > 12 files changed, 26 insertions(+), 26 deletions(-) > > > > diff --git a/arch/Kconfig b/arch/Kconfig > > index 56b6ccc0e32d..56d4752b6db6 100644 > > --- a/arch/Kconfig > > +++ b/arch/Kconfig > > @@ -1028,6 +1028,9 @@ config HAVE_STATIC_CALL_INLINE > > bool > > depends on HAVE_STATIC_CALL > > +config ARCH_SUPPORTS_DEBUG_PAGEALLOC > > + bool > > + > > source "kernel/gcov/Kconfig" > > source "scripts/gcc-plugins/Kconfig" > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index 1d466addb078..a932810cfd90 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -71,6 +71,7 @@ config ARM64 > > select ARCH_USE_QUEUED_RWLOCKS > > select ARCH_USE_QUEUED_SPINLOCKS > > select ARCH_USE_SYM_ANNOTATIONS > > + select ARCH_SUPPORTS_DEBUG_PAGEALLOC > > select ARCH_SUPPORTS_MEMORY_FAILURE > > select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK > > select ARCH_SUPPORTS_ATOMIC_RMW > > @@ -1025,9 +1026,6 @@ config HOLES_IN_ZONE > > source "kernel/Kconfig.hz" > > -config ARCH_SUPPORTS_DEBUG_PAGEALLOC > > - def_bool y > > - > > config ARCH_SPARSEMEM_ENABLE > > def_bool y > > select SPARSEMEM_VMEMMAP_ENABLE > > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > > index 1b94f5b82654..439325532be1 100644 > > --- a/arch/arm64/mm/pageattr.c > > +++ b/arch/arm64/mm/pageattr.c > > @@ -155,7 +155,7 @@ int set_direct_map_invalid_noflush(struct page *page) > > .clear_mask = __pgprot(PTE_VALID), > > }; > > - if (!rodata_full) > > + if (!debug_pagealloc_enabled() && !rodata_full) > > return 0; > > return apply_to_page_range(&init_mm, > > @@ -170,7 +170,7 @@ int set_direct_map_default_noflush(struct page *page) > > .clear_mask = __pgprot(PTE_RDONLY), > > }; > > - if (!rodata_full) > > + if (!debug_pagealloc_enabled() && !rodata_full) > > return 0; > > return apply_to_page_range(&init_mm, > > I don't understand these two hunks. Previous patch calls this for > hibernation when CONFIG_ARCH_HAS_SET_DIRECT_MAP, which is true for arm64. > Why suddenly this starts to depend on debug_pagealloc_enabled()? I was confused about this for quite a long :) On arm64 the changes to direct^w linear map are allowed when debug_page_alloc() || rodata_full In hibernation we essentially have now if (1) set_direct_map(something) else debug_page_alloc_map() With debug_pagealloc enabled but with rodata_full disabled arm64 versions of set_direct_map_*() will become a nop, so a page that was unmapped by debug_pagealloc() will not be mapped back. I'm still puzzled how hibernation might ever need to save a free page, but that's another story. -- Sincerely yours, Mike.