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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EE61CCD1284 for ; Tue, 2 Apr 2024 19:06:38 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=hwwp3R1q; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4V8HRd3wX7z3dW4 for ; Wed, 3 Apr 2024 06:06:37 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=hwwp3R1q; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=139.178.84.217; helo=dfw.source.kernel.org; envelope-from=nathan@kernel.org; receiver=lists.ozlabs.org) Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4V8HQq6KJRz3bsd for ; Wed, 3 Apr 2024 06:05:55 +1100 (AEDT) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id DCD8861069; Tue, 2 Apr 2024 19:05:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 174E5C433C7; Tue, 2 Apr 2024 19:05:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712084752; bh=ivObVSKpIkBqCwHlwbBnTW/chcdv4hxzzU2Dqfw4oFY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hwwp3R1q+T6P3wBULlM9JHA7unNDdzQ7FyQAUtX0BWJYLvoTcSvvCHVjCZCIVdCpp P3hH9eiYczkxNqEPQVprmxEGBBjdTDkm2i0W/ywueVCqBxiyfNB/jd8/8ayTftnI02 M4H/eOWh4bn/Ygw7g56bJeYODFwZcPWGYCkn3uSNTytEJ/MI/De15gQoC2yuWB5IGj wAuTXHpQOJnJxkjgdHehxG1bRSCJBtOySRaGeOy42ZdtKoUpS5CRRoEU1D0PnH0iBU 8Uk+I9y88XUSxVMrMygH39vnWX8Uwf8mWiw+V7NK/hpKeE+IqP03OkudSXAlGSwaK8 pTIHCarE2rCRw== Date: Tue, 2 Apr 2024 12:05:49 -0700 From: Nathan Chancellor To: peterx@redhat.com Subject: Re: [PATCH v4 05/13] mm/arch: Provide pud_pfn() fallback Message-ID: <20240402190549.GA706730@dev-arch.thelio-3990X> References: <20240327152332.950956-1-peterx@redhat.com> <20240327152332.950956-6-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240327152332.950956-6-peterx@redhat.com> 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: James Houghton , David Hildenbrand , Yang Shi , Andrew Jones , linux-mm@kvack.org, Matthew Wilcox , linux-riscv@lists.infradead.org, WANG Xuerui , Andrea Arcangeli , Christoph Hellwig , Huacai Chen , "Aneesh Kumar K . V" , linux-arm-kernel@lists.infradead.org, Jason Gunthorpe , Axel Rasmussen , Rik van Riel , John Hubbard , loongarch@lists.linux.dev, "Kirill A . Shutemov" , Vlastimil Babka , Lorenzo Stoakes , Muchun Song , linux-kernel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, Mike Rapoport , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Peter (and LoongArch folks), On Wed, Mar 27, 2024 at 11:23:24AM -0400, peterx@redhat.com wrote: > From: Peter Xu > > The comment in the code explains the reasons. We took a different approach > comparing to pmd_pfn() by providing a fallback function. > > Another option is to provide some lower level config options (compare to > HUGETLB_PAGE or THP) to identify which layer an arch can support for such > huge mappings. However that can be an overkill. > > Cc: Mike Rapoport (IBM) > Cc: Matthew Wilcox > Reviewed-by: Jason Gunthorpe > Signed-off-by: Peter Xu > --- > arch/riscv/include/asm/pgtable.h | 1 + > arch/s390/include/asm/pgtable.h | 1 + > arch/sparc/include/asm/pgtable_64.h | 1 + > arch/x86/include/asm/pgtable.h | 1 + > include/linux/pgtable.h | 10 ++++++++++ > 5 files changed, 14 insertions(+) > > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > index 20242402fc11..0ca28cc8e3fa 100644 > --- a/arch/riscv/include/asm/pgtable.h > +++ b/arch/riscv/include/asm/pgtable.h > @@ -646,6 +646,7 @@ static inline unsigned long pmd_pfn(pmd_t pmd) > > #define __pud_to_phys(pud) (__page_val_to_pfn(pud_val(pud)) << PAGE_SHIFT) > > +#define pud_pfn pud_pfn > static inline unsigned long pud_pfn(pud_t pud) > { > return ((__pud_to_phys(pud) & PUD_MASK) >> PAGE_SHIFT); > diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h > index 1a71cb19c089..6cbbe473f680 100644 > --- a/arch/s390/include/asm/pgtable.h > +++ b/arch/s390/include/asm/pgtable.h > @@ -1414,6 +1414,7 @@ static inline unsigned long pud_deref(pud_t pud) > return (unsigned long)__va(pud_val(pud) & origin_mask); > } > > +#define pud_pfn pud_pfn > static inline unsigned long pud_pfn(pud_t pud) > { > return __pa(pud_deref(pud)) >> PAGE_SHIFT; > diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h > index 4d1bafaba942..26efc9bb644a 100644 > --- a/arch/sparc/include/asm/pgtable_64.h > +++ b/arch/sparc/include/asm/pgtable_64.h > @@ -875,6 +875,7 @@ static inline bool pud_leaf(pud_t pud) > return pte_val(pte) & _PAGE_PMD_HUGE; > } > > +#define pud_pfn pud_pfn > static inline unsigned long pud_pfn(pud_t pud) > { > pte_t pte = __pte(pud_val(pud)); > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index cefc7a84f7a4..273f7557218c 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -234,6 +234,7 @@ static inline unsigned long pmd_pfn(pmd_t pmd) > return (pfn & pmd_pfn_mask(pmd)) >> PAGE_SHIFT; > } > > +#define pud_pfn pud_pfn > static inline unsigned long pud_pfn(pud_t pud) > { > phys_addr_t pfn = pud_val(pud); > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h > index 600e17d03659..75fe309a4e10 100644 > --- a/include/linux/pgtable.h > +++ b/include/linux/pgtable.h > @@ -1817,6 +1817,16 @@ typedef unsigned int pgtbl_mod_mask; > #define pte_leaf_size(x) PAGE_SIZE > #endif > > +/* > + * We always define pmd_pfn for all archs as it's used in lots of generic > + * code. Now it happens too for pud_pfn (and can happen for larger > + * mappings too in the future; we're not there yet). Instead of defining > + * it for all archs (like pmd_pfn), provide a fallback. > + */ > +#ifndef pud_pfn > +#define pud_pfn(x) ({ BUILD_BUG(); 0; }) > +#endif > + > /* > * Some architectures have MMUs that are configurable or selectable at boot > * time. These lead to variable PTRS_PER_x. For statically allocated arrays it > -- > 2.44.0 > This BUILD_BUG() triggers for LoongArch with their defconfig, so it seems like they need to provide an implementation of pud_pfn()? In function 'follow_huge_pud', inlined from 'follow_pud_mask' at mm/gup.c:1075:10, inlined from 'follow_p4d_mask' at mm/gup.c:1105:9, inlined from 'follow_page_mask' at mm/gup.c:1151:10: include/linux/compiler_types.h:460:45: error: call to '__compiletime_assert_382' declared with attribute error: BUILD_BUG failed 460 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) | ^ include/linux/compiler_types.h:441:25: note: in definition of macro '__compiletime_assert' 441 | prefix ## suffix(); \ | ^~~~~~ include/linux/compiler_types.h:460:9: note: in expansion of macro '_compiletime_assert' 460 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) | ^~~~~~~~~~~~~~~~~~~ include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) | ^~~~~~~~~~~~~~~~~~ include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG' 59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") | ^~~~~~~~~~~~~~~~ include/linux/pgtable.h:1887:23: note: in expansion of macro 'BUILD_BUG' 1887 | #define pud_pfn(x) ({ BUILD_BUG(); 0; }) | ^~~~~~~~~ mm/gup.c:679:29: note: in expansion of macro 'pud_pfn' 679 | unsigned long pfn = pud_pfn(pud); | ^~~~~~~ Cheers, Nathan