From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f49.google.com (mail-pb0-f49.google.com [209.85.160.49]) by kanga.kvack.org (Postfix) with ESMTP id 86BFC6B0031 for ; Thu, 13 Feb 2014 18:20:22 -0500 (EST) Received: by mail-pb0-f49.google.com with SMTP id up15so11426129pbc.22 for ; Thu, 13 Feb 2014 15:20:22 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id x3si3535314pbf.241.2014.02.13.15.20.10 for ; Thu, 13 Feb 2014 15:20:10 -0800 (PST) Date: Thu, 13 Feb 2014 15:20:09 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: numa: bugfix for LAST_CPUPID_NOT_IN_PAGE_FLAGS Message-Id: <20140213152009.b16a30d2a5b5c5706fc8952a@linux-foundation.org> In-Reply-To: <1391563546-26052-1-git-send-email-pingfank@linux.vnet.ibm.com> References: <1391563546-26052-1-git-send-email-pingfank@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Liu Ping Fan Cc: linux-mm@kvack.org, Peter Zijlstra , Benjamin Herrenschmidt , Paul Mackerras , "Aneesh Kumar K.V" , linuxppc-dev@lists.ozlabs.org On Wed, 5 Feb 2014 09:25:46 +0800 Liu Ping Fan wrote: > When doing some numa tests on powerpc, I triggered an oops bug. I find > it is caused by using page->_last_cpupid. It should be initialized as > "-1 & LAST_CPUPID_MASK", but not "-1". Otherwise, in task_numa_fault(), > we will miss the checking (last_cpupid == (-1 & LAST_CPUPID_MASK)). > And finally cause an oops bug in task_numa_group(), since the online cpu is > less than possible cpu. I grabbed this. I added this to the changelog: : PPC needs the LAST_CPUPID_NOT_IN_PAGE_FLAGS case because ppc needs to : support a large physical address region, up to 2^46 but small section size : (2^24). So when NR_CPUS grows up, it is easily to cause : not-in-page-flags. to hopefully address Peter's observation. How should we proceed with this? I'm getting the impression that numa balancing on ppc is a dead duck in 3.14, so perhaps this and powerpc-mm-add-new-set-flag-argument-to-pte-pmd-update-function.patch mm-dirty-accountable-change-only-apply-to-non-prot-numa-case.patch mm-use-ptep-pmdp_set_numa-for-updating-_page_numa-bit.patch are 3.15-rc1 material? -- 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