From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 3CA2A6B0038 for ; Thu, 18 May 2017 01:21:13 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id b74so24708178pfd.2 for ; Wed, 17 May 2017 22:21:13 -0700 (PDT) Received: from ozlabs.org (ozlabs.org. [2401:3900:2:1::2]) by mx.google.com with ESMTPS id h1si4136292plh.157.2017.05.17.22.21.11 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 May 2017 22:21:12 -0700 (PDT) From: Michael Ellerman Subject: Re: [PATCH v3 2/2] powerpc/mm/hugetlb: Add support for 1G huge pages In-Reply-To: <1494995292-4443-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1494995292-4443-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1494995292-4443-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Date: Thu, 18 May 2017 15:21:09 +1000 Message-ID: <87fug2loze.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: "Aneesh Kumar K.V" , akpm@linux-foundation.org, Anshuman Khandual Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org "Aneesh Kumar K.V" writes: > POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch > enables the usage of 1G page size for hugetlbfs. This also update the helper > such we can do 1G page allocation at runtime. > > We still don't enable 1G page size on DD1 version. This is to avoid doing > workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add > radix__tlb_flush_pte_p9_dd1() > > Signed-off-by: Aneesh Kumar K.V > --- > arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++ > arch/powerpc/mm/hugetlbpage.c | 7 +++++-- > arch/powerpc/platforms/Kconfig.cputype | 1 + > 3 files changed, 16 insertions(+), 2 deletions(-) I think this patch is OK, but it's very confusing because it doesn't mention that it's only talking about *generic* gigantic page support. We have existing support for gigantic pages on powerpc, on several platforms. This patch appears to break that, but I think doesn't in practice? So can you make it a bit clearer in the commit message, and the code, that this is only about enabling the generic gigantic page support, and is unrelated to the arch-specific gigantic page support. cheers > diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h > index 6666cd366596..5c28bd6f2ae1 100644 > --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h > +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h > @@ -50,4 +50,14 @@ static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, > else > return entry; > } > + > +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE > +static inline bool gigantic_page_supported(void) > +{ > + if (radix_enabled()) > + return true; > + return false; > +} > +#endif > + > #endif > diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c > index a4f33de4008e..80f6d2ed551a 100644 > --- a/arch/powerpc/mm/hugetlbpage.c > +++ b/arch/powerpc/mm/hugetlbpage.c > @@ -763,8 +763,11 @@ static int __init add_huge_page_size(unsigned long long size) > * Hash: 16M and 16G > */ > if (radix_enabled()) { > - if (mmu_psize != MMU_PAGE_2M) > - return -EINVAL; > + if (mmu_psize != MMU_PAGE_2M) { > + if (cpu_has_feature(CPU_FTR_POWER9_DD1) || > + (mmu_psize != MMU_PAGE_1G)) > + return -EINVAL; > + } > } else { > if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G) > return -EINVAL; > diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype > index 684e886eaae4..b76ef6637016 100644 > --- a/arch/powerpc/platforms/Kconfig.cputype > +++ b/arch/powerpc/platforms/Kconfig.cputype > @@ -344,6 +344,7 @@ config PPC_STD_MMU_64 > config PPC_RADIX_MMU > bool "Radix MMU Support" > depends on PPC_BOOK3S_64 > + select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA > default y > help > Enable support for the Power ISA 3.0 Radix style MMU. Currently this > -- > 2.7.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org