From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Kirill A. Shutemov" Subject: Re: [RFC PATCH v2 05/11] mm: thp: Correct the HPAGE_PMD_ORDER check. Date: Wed, 8 May 2013 15:44:17 +0300 Message-ID: <20130508124417.GA29631@shutemov.name> References: <1368006763-30774-1-git-send-email-steve.capper@linaro.org> <1368006763-30774-6-git-send-email-steve.capper@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1368006763-30774-6-git-send-email-steve.capper@linaro.org> Sender: owner-linux-mm@kvack.org To: Steve Capper Cc: linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Michal Hocko , Ken Chen , Mel Gorman , Catalin Marinas , Will Deacon , patches@linaro.org List-Id: linux-arch.vger.kernel.org On Wed, May 08, 2013 at 10:52:37AM +0100, Steve Capper wrote: > All Transparent Huge Pages are allocated by the buddy allocator. > > A compile time check is in place that fails when the order of a > transparent huge page is too large to be allocated by the buddy > allocator. Unfortunately that compile time check passes when: > HPAGE_PMD_ORDER == MAX_ORDER > ( which is incorrect as the buddy allocator can only allocate > memory of order strictly less than MAX_ORDER. ) It looks confusing to me. Shouldn't we fix what MAX_ORDER means instead? -- Kirill A. Shutemov -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from shutemov.name ([204.155.152.216]:37915 "EHLO shutemov.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752317Ab3EHL6L (ORCPT ); Wed, 8 May 2013 07:58:11 -0400 Date: Wed, 8 May 2013 15:44:17 +0300 From: "Kirill A. Shutemov" Subject: Re: [RFC PATCH v2 05/11] mm: thp: Correct the HPAGE_PMD_ORDER check. Message-ID: <20130508124417.GA29631@shutemov.name> References: <1368006763-30774-1-git-send-email-steve.capper@linaro.org> <1368006763-30774-6-git-send-email-steve.capper@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1368006763-30774-6-git-send-email-steve.capper@linaro.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Steve Capper Cc: linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Michal Hocko , Ken Chen , Mel Gorman , Catalin Marinas , Will Deacon , patches@linaro.org Message-ID: <20130508124417.7EPzAgsIm1F1dMHX0zm_IPia8vgeRU4HsuTx6pSs3XM@z> On Wed, May 08, 2013 at 10:52:37AM +0100, Steve Capper wrote: > All Transparent Huge Pages are allocated by the buddy allocator. > > A compile time check is in place that fails when the order of a > transparent huge page is too large to be allocated by the buddy > allocator. Unfortunately that compile time check passes when: > HPAGE_PMD_ORDER == MAX_ORDER > ( which is incorrect as the buddy allocator can only allocate > memory of order strictly less than MAX_ORDER. ) It looks confusing to me. Shouldn't we fix what MAX_ORDER means instead? -- Kirill A. Shutemov