Messages in this thread | | | Date | Wed, 23 Sep 2020 08:52:38 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 3/5] mm: Rework return value for copy_one_pte() |
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On 09/22, Peter Xu wrote: > > On Tue, Sep 22, 2020 at 08:23:18PM +0200, Oleg Nesterov wrote: > > > > But I still think that !pte_none() -> pte_none() transition is not possible > > under mmap_write_lock()... > > > > OK, let me repeat I don't understans these code paths enough, let me reword: > > I don't see how this transition is possible. > > Though I guess I'll keep my wording, because I still think it's accurate to > me. :) > > Can we e.g. punch a page hole without changing vmas?
punch a hole? I don't know what does it mean...
However, I think you are right anyway. I forgot that (at least) truncate can clear this pte without mmap_sem after pte_unmap_unlock().
So I think you are right, the current code is wrong too.
Thanks!
Oleg.
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