From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753870Ab1ASWuY (ORCPT ); Wed, 19 Jan 2011 17:50:24 -0500 Received: from mail-fx0-f46.google.com ([209.85.161.46]:52290 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751781Ab1ASWuX (ORCPT ); Wed, 19 Jan 2011 17:50:23 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=qrzA6FYe4N/kIU2CCix06bjyqxUZjxoNToVOfujKKCfP4yTdlAgm67B31M3MxGj3cZ 3oUo6vZd7WGqAaOBubIpEaYPI/FwZNPHxnijVER3FO7x+xvas1hjZVt0Pi4TR5/+h8uE 7caQ0u47aHIMk42xbQkLuqPB9Sz6nB7XPAtZA= Date: Thu, 20 Jan 2011 00:49:50 +0200 From: Ilya Dryomov To: Andrea Arcangeli Cc: linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org, idryomov@gmail.com Subject: Re: [BUG] BUG: unable to handle kernel paging request at fffba000 Message-ID: <20110119224950.GA3429@kwango.lan.net> References: <20110119124047.GA30274@kwango.lan.net> <20110119221909.GO9506@random.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110119221909.GO9506@random.random> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 19, 2011 at 11:19:09PM +0100, Andrea Arcangeli wrote: > Hello Ilya, > > thanks for sending me the gdb info too. > > can you test this fix? Thanks a lot! (it only affected x86 32bit > builds with highpte enabled) > > ==== > Subject: fix pte_unmap in khugepaged 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 It fixes the above problem for me. Thanks a lot Andrea. > --- > > 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); >