From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e31.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m4TCZZG1018331 for ; Thu, 29 May 2008 08:35:35 -0400 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m4TCZYVR040364 for ; Thu, 29 May 2008 06:35:35 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m4TCZYI4026413 for ; Thu, 29 May 2008 06:35:34 -0600 Subject: Re: [patch] hugetlb: fix lockdep error From: Adam Litke In-Reply-To: <20080528201929.cf766924.akpm@linux-foundation.org> References: <20080529015956.GC3258@wotan.suse.de> <20080528191657.ba5f283c.akpm@linux-foundation.org> <20080529022919.GD3258@wotan.suse.de> <20080528193808.6e053dac.akpm@linux-foundation.org> <20080529030745.GG3258@wotan.suse.de> <20080528201929.cf766924.akpm@linux-foundation.org> Content-Type: text/plain Date: Thu, 29 May 2008 07:35:37 -0500 Message-Id: <1212064537.12036.85.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Nick Piggin , nacc@us.ibm.com, Linux Memory Management List , kosaki.motohiro@jp.fujitsu.com List-ID: On Wed, 2008-05-28 at 20:19 -0700, Andrew Morton wrote: > On Thu, 29 May 2008 05:07:45 +0200 Nick Piggin wrote: > > > > > mm/hugetlb.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > Index: linux-2.6/mm/hugetlb.c > > > > =================================================================== > > > > --- linux-2.6.orig/mm/hugetlb.c > > > > +++ linux-2.6/mm/hugetlb.c > > > > @@ -785,7 +785,7 @@ int copy_hugetlb_page_range(struct mm_st > > > > continue; > > > > > > > > spin_lock(&dst->page_table_lock); > > > > - spin_lock(&src->page_table_lock); > > > > + spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING); > > > > if (!huge_pte_none(huge_ptep_get(src_pte))) { > > > > if (cow) > > > > huge_ptep_set_wrprotect(src, addr, src_pte); > > > > > > Confused. This code has been there since October 2005. Why are we > > > only seeing lockdep warnings now? > > > > Can't say. Haven't looked at hugetlb code or tested it much until now. > > I am using a recent libhugetlbfs test suite, FWIW. > > I don't believe that it's possible that nobody has run that test suite > with lockdep enabled at any time in the past three years. I have to confess that I have seen this from time to time. Since it was clearly a false positive, it was easy to get distracted by other things. I'll go and update all my default kernel configs to turn on everything all the time so things like this annoy me until I fix them. -- Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center -- 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/ . Don't email: email@kvack.org