Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932707AbaLAXzt (ORCPT ); Mon, 1 Dec 2014 18:55:49 -0500 Received: from gate.crashing.org ([63.228.1.57]:44082 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753315AbaLAXzs (ORCPT ); Mon, 1 Dec 2014 18:55:48 -0500 Message-ID: <1417473519.7182.6.camel@kernel.crashing.org> Subject: Re: [PATCH 02/10] mm: Add p[te|md] protnone helpers for use by NUMA balancing From: Benjamin Herrenschmidt To: Mel Gorman Cc: Linux Kernel , Linux-MM , LinuxPPC-dev , Aneesh Kumar , Hugh Dickins , Dave Jones , Rik van Riel , Ingo Molnar , Kirill Shutemov , Sasha Levin , Paul Mackerras , Linus Torvalds Date: Tue, 02 Dec 2014 09:38:39 +1100 In-Reply-To: <1416578268-19597-3-git-send-email-mgorman@suse.de> References: <1416578268-19597-1-git-send-email-mgorman@suse.de> <1416578268-19597-3-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2014-11-21 at 13:57 +0000, Mel Gorman wrote: > #ifdef CONFIG_NUMA_BALANCING > +/* > + * These work without NUMA balancing but the kernel does not care. See the > + * comment in include/asm-generic/pgtable.h > + */ > +static inline int pte_protnone(pte_t pte) > +{ > + return (pte_val(pte) & > + (_PAGE_PRESENT | _PAGE_USER)) == _PAGE_PRESENT; > +} I would add a comment clarifying that this only works for user pages, ie, this accessor will always return "true" for a kernel page on ppc. > +static inline int pmd_protnone(pmd_t pmd) > +{ > + return pte_protnone(pmd_pte(pmd)); > +} > + > static inline int pte_present(pte_t pte) > { > return pte_val(pte) & _PAGE_NUMA_MASK; > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index 081d6f4..2e25780 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -502,6 +502,22 @@ static inline int pmd_present(pmd_t pmd) > _PAGE_NUMA); > } > > +#ifdef CONFIG_NUMA_BALANCING > +/* > + * These work without NUMA balancing but the kernel does not care. See the > + * comment in include/asm-generic/pgtable.h > + */ > +static inline int pte_protnone(pte_t pte) > +{ > + return pte_flags(pte) & _PAGE_PROTNONE; > +} > + > +static inline int pmd_protnone(pmd_t pmd) > +{ > + return pmd_flags(pmd) & _PAGE_PROTNONE; > +} > +#endif /* CONFIG_NUMA_BALANCING */ > + > static inline int pmd_none(pmd_t pmd) > { > /* Only check low word on 32-bit platforms, since it might be > diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h > index 177d597..d497d08 100644 > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -688,6 +688,26 @@ static inline int pmd_trans_unstable(pmd_t *pmd) > #endif > } > > +#ifndef CONFIG_NUMA_BALANCING > +/* > + * Technically a PTE can be PROTNONE even when not doing NUMA balancing but > + * the only case the kernel cares is for NUMA balancing and is only ever set > + * when the VMA is accessible. For PROT_NONE VMAs, the PTEs are not marked > + * _PAGE_PROTNONE so by by default, implement the helper as "always no". It > + * is the responsibility of the caller to distinguish between PROT_NONE > + * protections and NUMA hinting fault protections. > + */ > +static inline int pte_protnone(pte_t pte) > +{ > + return 0; > +} > + > +static inline int pmd_protnone(pmd_t pmd) > +{ > + return 0; > +} > +#endif /* CONFIG_NUMA_BALANCING */ > + > #ifdef CONFIG_NUMA_BALANCING > /* > * _PAGE_NUMA distinguishes between an unmapped page table entry, an entry that -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/