Re: [patch] hugetlb: fix lockdep error

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 29 May 2008 05:07:45 +0200 Nick Piggin <npiggin@suse.de> 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.

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.

(sheesh)

--
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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>