From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754904Ab2LGWeR (ORCPT ); Fri, 7 Dec 2012 17:34:17 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:43011 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751128Ab2LGWeP (ORCPT ); Fri, 7 Dec 2012 17:34:15 -0500 Date: Fri, 7 Dec 2012 14:34:14 -0800 From: Andrew Morton To: Naoya Horiguchi Cc: aneesh.kumar@linux.vnet.ibm.com, Andi Kleen , Tony Luck , Wu Fengguang , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/3] HWPOISON, hugetlbfs: fix warning on freeing hwpoisoned hugepage Message-Id: <20121207143414.b2d33095.akpm@linux-foundation.org> In-Reply-To: <1354895397-21736-1-git-send-email-n-horiguchi@ah.jp.nec.com> References: <878v9acn5m.fsf@linux.vnet.ibm.com> <1354895397-21736-1-git-send-email-n-horiguchi@ah.jp.nec.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 7 Dec 2012 10:49:57 -0500 Naoya Horiguchi wrote: > This patch fixes the warning from __list_del_entry() which is triggered > when a process tries to do free_huge_page() for a hwpoisoned hugepage. This changelog is very short. In fact it is too short, resulting in others having to ask questions about the patch. When this happens, please treat it as a sign that the changelog needs additional information - so that other readers will not feel a need to ask the same questions! I added this paragraph: : free_huge_page() can be called for hwpoisoned hugepage from : unpoison_memory(). This function gets refcount once and clears : PageHWPoison, and then puts refcount twice to return the hugepage back to : free pool. The second put_page() finally reaches free_huge_page(). Also, is the description accurate? Is the __list_del_entry() warning the only problem? Or is it the case that this bug will cause memory corruption? If so then the patch is pretty important and is probably needed in -stable as well? I haven't checked how far back in time the bug exists.