Messages in this thread | | | Date | Tue, 18 Mar 2014 18:10:40 -0700 | Subject | Re: bad rss-counter message in 3.14rc5 | From | Linus Torvalds <> |
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On Tue, Mar 18, 2014 at 5:38 PM, Hugh Dickins <hughd@google.com> wrote: > > And yes, it is possible (though very unusual) to find an anon page or > swap entry in a VM_SHARED nonlinear mapping: coming from that horrid > get_user_pages(write, force) case which COWs even in a shared mapping.
Hmm. Maybe we could just disallow that forced case.
It *used* to be a trivial "we can just do a COW", but that was back when the VM was much simpler and we had no rmap's etc. So "that horrid case" used to be a simple hack that wasn't painful. But I suspect we could very easily just fail it instead of forcing a COW, if that would make it simpler for the VM code.
Linus
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