From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by fg-out-1718.google.com with SMTP id 19so1915347fgg.4 for ; Wed, 28 May 2008 20:48:37 -0700 (PDT) Message-ID: <29495f1d0805282048s5c699e70rf4ab1377b18f337e@mail.gmail.com> Date: Wed, 28 May 2008 20:48:36 -0700 From: "Nish Aravamudan" Subject: Re: [patch] hugetlb: fix lockdep error In-Reply-To: <20080528201929.cf766924.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline 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> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Nick Piggin , agl@us.ibm.com, nacc@us.ibm.com, Linux Memory Management List , kosaki.motohiro@jp.fujitsu.com List-ID: On 5/28/08, 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 can't tell from Nick's mail if the lockdep error is specific to this particular testcase or not, but if so, that would make it the past two (almost three) months, as that was when this particular testcase was added. And I'm not sure when we released the first development snapshot that would have included it (for non-git users, that is). In any case, I also don't know how we wouldn't have seen this issue on our systems and that's a problem. I will make a concerted effort to work with the other libhugetlbfs developers to make sure all possible debug options are on (as you've pointed out to me elsewhere/when). Thanks, Nish -- 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