Messages in this thread | | | Date | Fri, 12 Jun 2009 12:07:44 +0200 | From | Nick Piggin <> | Subject | Re: [PATCH 2/5] HWPOISON: fix tasklist_lock/anon_vma locking order |
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On Fri, Jun 12, 2009 at 12:03:08PM +0200, Andi Kleen wrote: > On Thu, Jun 11, 2009 at 10:22:41PM +0800, Wu Fengguang wrote: > > To avoid possible deadlock. Proposed by Nick Piggin: > > I disagree with the description. There's no possible deadlock right now. > It would be purely out of paranoia. > > > > > You have tasklist_lock(R) nesting outside i_mmap_lock, and inside anon_vma > > lock. And anon_vma lock nests inside i_mmap_lock. > > > > This seems fragile. If rwlocks ever become FIFO or tasklist_lock changes > > I was a bit dubious on this reasoning. If rwlocks become FIFO a lot of > stuff will likely break. > > > type (maybe -rt kernels do it), then you could have a task holding > > I think they tried but backed off quickly again > > It's ok with a less scare-mongering description.
There's simply no good reason to invert ordering of locks like this.
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