From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f178.google.com (mail-ob0-f178.google.com [209.85.214.178]) by kanga.kvack.org (Postfix) with ESMTP id D86896B0038 for ; Tue, 3 Mar 2015 18:15:13 -0500 (EST) Received: by obbnt9 with SMTP id nt9so3246907obb.13 for ; Tue, 03 Mar 2015 15:15:13 -0800 (PST) Received: from g9t5008.houston.hp.com (g9t5008.houston.hp.com. [15.240.92.66]) by mx.google.com with ESMTPS id 7si1133619obr.79.2015.03.03.15.15.12 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 03 Mar 2015 15:15:12 -0800 (PST) Message-ID: <1425424472.17007.191.camel@misato.fc.hp.com> Subject: Re: [PATCH v3 6/6] x86, mm: Support huge KVA mappings on x86 From: Toshi Kani Date: Tue, 03 Mar 2015 16:14:32 -0700 In-Reply-To: <20150303144414.9f97ef25ad8aed7d112896bf@linux-foundation.org> References: <1425404664-19675-1-git-send-email-toshi.kani@hp.com> <1425404664-19675-7-git-send-email-toshi.kani@hp.com> <20150303144414.9f97ef25ad8aed7d112896bf@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, arnd@arndb.de, linux-mm@kvack.org, x86@kernel.org, linux-kernel@vger.kernel.org, dave.hansen@intel.com, Elliott@hp.com On Tue, 2015-03-03 at 14:44 -0800, Andrew Morton wrote: > On Tue, 3 Mar 2015 10:44:24 -0700 Toshi Kani wrote: : > > + > > +#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP > > +int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) > > +{ > > + u8 mtrr; > > + > > + /* > > + * Do not use a huge page when the range is covered by non-WB type > > + * of MTRRs. > > + */ > > + mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE); > > + if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF)) > > + return 0; > > It would be good to notify the operator in some way when this happens. > Otherwise the kernel will run more slowly and there's no way of knowing > why. I guess slap a pr_info() in there. Or maybe pr_warn()? We only use 4KB mappings today, so this case will not make it run slowly, i.e. it will be the same as today. Also, adding a message here can generate a lot of messages when MTRRs cover a large area. So, I think we are fine without a message. > > > + prot = pgprot_4k_2_large(prot); > > + > > + set_pte((pte_t *)pud, pfn_pte( > > + (u64)addr >> PAGE_SHIFT, > > + __pgprot(pgprot_val(prot) | _PAGE_PSE))); > > + > > + return 1; > > +} > > + > > +int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot) > > +{ > > + u8 mtrr; > > + > > + /* > > + * Do not use a huge page when the range is covered by non-WB type > > + * of MTRRs. > > + */ > > + mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE); > > + if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF)) > > + return 0; > > + > > + prot = pgprot_4k_2_large(prot); > > + > > + set_pte((pte_t *)pmd, pfn_pte( > > + (u64)addr >> PAGE_SHIFT, > > + __pgprot(pgprot_val(prot) | _PAGE_PSE))); > > + > > + return 1; > > +} > > > > +int pud_clear_huge(pud_t *pud) > > +{ > > + if (pud_large(*pud)) { > > + pud_clear(pud); > > + return 1; > > + } > > + > > + return 0; > > +} > > + > > +int pmd_clear_huge(pmd_t *pmd) > > +{ > > + if (pmd_large(*pmd)) { > > + pmd_clear(pmd); > > + return 1; > > + } > > + > > + return 0; > > +} > > I didn't see anywhere where the return values of these functions are > documented. It's all fairly obvious, but we could help the rearers > a bit. Agreed. I will add function headers with descriptions to the new functions. Thanks, -Toshi -- 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