Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764446AbYCDVxx (ORCPT ); Tue, 4 Mar 2008 16:53:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752795AbYCDVxp (ORCPT ); Tue, 4 Mar 2008 16:53:45 -0500 Received: from e1.ny.us.ibm.com ([32.97.182.141]:42377 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751921AbYCDVxo (ORCPT ); Tue, 4 Mar 2008 16:53:44 -0500 Subject: Re: [BUG] 2.6.25-rc3-mm1 kernel bug while running libhugetlbfs From: Adam Litke To: Andrew Morton Cc: Kamalesh Babulal , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, apw@shadowen.org, balbir@linux.vnet.ibm.com In-Reply-To: <20080304115158.505f33eb.akpm@linux-foundation.org> References: <20080304011928.e8c82c0c.akpm@linux-foundation.org> <47CDA0F1.9030908@linux.vnet.ibm.com> <20080304115158.505f33eb.akpm@linux-foundation.org> Content-Type: text/plain Organization: IBM Date: Tue, 04 Mar 2008 16:01:29 -0600 Message-Id: <1204668089.14779.92.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.12.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1640 Lines: 45 On Tue, 2008-03-04 at 11:51 -0800, Andrew Morton wrote: > hugetlb-correct-page-count-for-surplus-huge-pages.patch adds: > > if (page) { > /* > * This page is now managed by the hugetlb allocator and has > * no users -- drop the buddy allocator's reference. > */ > int page_count = put_page_testzero(page); > BUG_ON(page_count != 0); > > Ugh I got bitten by put_page_testzero(). When it returns 1, the page count is zero (not the page count). My initial version had a BUG_ON() with side-effects. When a reviewer pointed it out, I thought I could fix the patch up on its way out the door. I have self-administered my punishment. This patch will fix it: Signed-off-by: Adam Litke --- mm/hugetlb.c.orig 2008-03-04 13:36:30.000000000 -0800 +++ mm/hugetlb.c 2008-03-04 13:39:30.000000000 -0800 @@ -291,8 +291,8 @@ static struct page *alloc_buddy_huge_pag * This page is now managed by the hugetlb allocator and has * no users -- drop the buddy allocator's reference. */ - int page_count = put_page_testzero(page); - BUG_ON(page_count != 0); + put_page_testzero(page); + VM_BUG_ON(page_count(page)); nid = page_to_nid(page); set_compound_page_dtor(page, free_huge_page); /* -- Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center -- 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/