From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754899Ab1ASWWo (ORCPT ); Wed, 19 Jan 2011 17:22:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:12207 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754552Ab1ASWWm (ORCPT ); Wed, 19 Jan 2011 17:22:42 -0500 Date: Wed, 19 Jan 2011 23:21:50 +0100 From: Andrea Arcangeli To: Borislav Petkov Cc: werner , linux-kernel@vger.kernel.org, linux-mm , Andrew Morton Subject: Re: 2.6.38-rc1 problems with khugepaged Message-ID: <20110119222150.GP9506@random.random> References: <20110119155954.GA2272@kryptos.osrc.amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110119155954.GA2272@kryptos.osrc.amd.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Werner, this should fix your oops, it's untested still so let me know if you test it. It's a noop for x86_64 and it only affected x86 32bit with highpte enabled. ==== Subject: khugepaged: fix pte_unmap for highpte x86_32 From: Andrea Arcangeli __collapse_huge_page_copy is still dereferencing the pte passed as parameter so we must pte_unmap after __collapse_huge_page_copy returns, not before. Signed-off-by: Andrea Arcangeli --- diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 004c9c2..c4f634b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1837,9 +1837,9 @@ static void collapse_huge_page(struct mm_struct *mm, spin_lock(ptl); isolated = __collapse_huge_page_isolate(vma, address, pte); spin_unlock(ptl); - pte_unmap(pte); if (unlikely(!isolated)) { + pte_unmap(pte); spin_lock(&mm->page_table_lock); BUG_ON(!pmd_none(*pmd)); set_pmd_at(mm, address, pmd, _pmd); @@ -1856,6 +1856,7 @@ static void collapse_huge_page(struct mm_struct *mm, anon_vma_unlock(vma->anon_vma); __collapse_huge_page_copy(pte, new_page, vma, address, ptl); + pte_unmap(pte); __SetPageUptodate(new_page); pgtable = pmd_pgtable(_pmd); VM_BUG_ON(page_count(pgtable) != 1);