Messages in this thread | | | Date | Tue, 30 Jul 2013 16:29:57 +0200 | From | Michal Hocko <> | Subject | Re: hugepage related lockdep trace. |
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On Mon 29-07-13 17:20:01, Peter Zijlstra wrote: > On Mon, Jul 29, 2013 at 04:53:08PM +0200, Michal Hocko wrote: > > Peter, for you context the lockdep splat has been reported > > here: https://lkml.org/lkml/2013/7/17/381 > > > > Minchan has proposed to workaround it by using SINGLE_DEPTH_NESTING > > https://lkml.org/lkml/2013/7/23/812 > > > > my idea was to use a separate class key for hugetlb as it is quite > > special in many ways: > > https://lkml.org/lkml/2013/7/25/277 > > > > What is the preferred way of fixing such an issue? > > The class is the safer annotation.
OK, I will use the class then. It should prevent other false positives AFAIU.
> That said; it is a rather horrible issue any which way. This PMD sharing > is very unique to hugetlbfs (also is that really worth the effort these > days?) and it will make it impossible to make hugetlbfs swappable.
No idea.
> The other solution is to make the pmd allocation GFP_NOFS.
That would be just papering over the lockdep limitation. So I would rather stick with something lockdep specific.
I will cook up a patch.
Thanks! -- Michal Hocko SUSE Labs
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