From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id F3B738D0039 for ; Thu, 10 Feb 2011 14:32:53 -0500 (EST) Received: from d01dlp02.pok.ibm.com (d01dlp02.pok.ibm.com [9.56.224.85]) by e9.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p1AJ7YZa010131 for ; Thu, 10 Feb 2011 14:07:37 -0500 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id EB7FA4DE8040 for ; Thu, 10 Feb 2011 14:31:59 -0500 (EST) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p1AJWpBF475546 for ; Thu, 10 Feb 2011 14:32:51 -0500 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p1AJWoih009273 for ; Thu, 10 Feb 2011 12:32:50 -0700 Subject: Re: [PATCH 4/5] teach smaps_pte_range() about THP pmds From: Dave Hansen In-Reply-To: <20110210180801.GA3347@random.random> References: <20110209195406.B9F23C9F@kernel> <20110209195411.816D55A7@kernel> <20110210180801.GA3347@random.random> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Thu, 10 Feb 2011 11:32:48 -0800 Message-ID: <1297366368.6737.14780.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael J Wolf , Johannes Weiner , David Rientjes On Thu, 2011-02-10 at 19:08 +0100, Andrea Arcangeli wrote: > the locking looks wrong, who is taking the &walk->mm->page_table_lock, > and isn't this going to deadlock on the pte_offset_map_lock for > NR_CPUS < 4, and where is it released? This spin_lock don't seem > necessary to me. > > The right locking would be: > > spin_lock(&walk->mm->page_table_lock); > if (pmd_trans_huge(*pmd)) { > if (pmd_trans_splitting(*pmd)) { > spin_unlock(&walk->mm->page_table_lock); > wait_split_huge_page(vma->anon_vma, pmd); > } else { > smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_SIZE, walk); > spin_unlock(&walk->mm->page_table_lock); > return 0; > } I was under the assumption that the mm->page_table_lock was already held here, but I think that's wrong. I'll go back, take another look, and retest. -- Dave -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org