Re: [PATCH 2/2] Futex non-page-pinning fix

[Jamie Lokier]

Andrew Morton wrote:
> Jamie Lokier <jamie@xxxxxxxxxxxxx> wrote:
> >
> > 	3. For (vma & VM_SHARED), look up futex_qs keyed on
> > 	   (vma->vm_file, vma->vm_pgoff + (uaddr - vma->vm_start) >>
> > 	   PAGE_SHIFT, offset).
> 
> That's a bit meaningless in non-linear mappings.

You think it's worth supporting futexes on non-linear mappings?
I see your point of view; they could be useful.

In that case, the (vma & VM_SHARED) case needs to look up the correct
pgoff or page after all.

It might be worth a VM_NONLINEAR flag, to skip walking the page table
in the non-linear case, but that's just an optimisation.

-- Jamie

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