From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 29 May 2008 05:26:58 +0200 From: Nick Piggin Subject: Re: [patch] hugetlb: fix lockdep error Message-ID: <20080529032658.GH3258@wotan.suse.de> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080528201929.cf766924.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: agl@us.ibm.com, nacc@us.ibm.com, Linux Memory Management List , kosaki.motohiro@jp.fujitsu.com List-ID: On Wed, May 28, 2008 at 08:19:29PM -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. Could be it was ignored as a false positive? > If that's really the case then perhaps we should make the ability to > recite Documentation/SubmitChecklist in three languages a prerequisite > for MM development. It does seem unusual, I don't know... Would it help to have a big button in kconfig called "test your kernel patches with this", which then selects various other things? -- 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