Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing

From	Hugh Dickins <hughd@google.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing
Date	2016-10-07 20:20 +0200
Message-ID	<spHUt-4gr-5@gated-at.bofh.it> (permalink)
References	(3 earlier) <slqfv-43C-19@gated-at.bofh.it> <slqyR-49T-5@gated-at.bofh.it> <spAgi-7f3-11@gated-at.bofh.it> <spFpD-2pN-31@gated-at.bofh.it> <spGc1-32z-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, 7 Oct 2016, Lorenzo Stoakes wrote:
> On Fri, Oct 07, 2016 at 08:34:15AM -0700, Linus Torvalds wrote:
> > Would you be willing to look at doing that kind of purely syntactic,
> > non-semantic cleanup first?
> 
> Sure, more than happy to do that! I'll work on a patch for this.
> 
> > I think that if we end up having the FOLL_FORCE semantics, we're
> > actually better off having an explicit FOLL_FORCE flag, and *not* do
> > some kind of implicit "under these magical circumstances we'll force
> > it anyway". The implicit thing is what we used to do long long ago, we
> > definitely don't want to.
> 
> That's a good point, it would definitely be considerably more 'magical', and
> expanding the conditions to include uprobes etc. would only add to that.
> 
> I wondered about an alternative parameter/flag but it felt like it was
> more-or-less FOLL_FORCE in a different form, at which point it may as well
> remain FOLL_FORCE :)

Adding Jan Kara (and Dave Hansen) to the Cc list: I think they were
pursuing get_user_pages() cleanups last year (which would remove the
force option from most callers anyway), and I've lost track of where
that all got to.  Lorenzo, please don't expend a lot of effort before
checking with Jan.

Hugh

Thread

Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Lorenzo Stoakes <lstoakes@gmail.com> - 2016-09-25 20:50 +0200
  Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-25 23:00 +0200
    Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-26 00:30 +0200
    Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Rik van Riel <riel@redhat.com> - 2016-09-26 00:40 +0200
      Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-26 01:00 +0200
        Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Hugh Dickins <hughd@google.com> - 2016-09-26 01:30 +0200
        Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Rik van Riel <riel@redhat.com> - 2016-09-26 02:50 +0200
          Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-26 03:10 +0200
        Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Lorenzo Stoakes <lstoakes@gmail.com> - 2016-10-07 12:10 +0200
          Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing Linus Torvalds <torvalds@linux-foundation.org> - 2016-10-07 17:40 +0200
            Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Lorenzo Stoakes <lstoakes@gmail.com> - 2016-10-07 18:30 +0200
              Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Hugh Dickins <hughd@google.com> - 2016-10-07 20:20 +0200
                Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Lorenzo Stoakes <lstoakes@gmail.com> - 2016-10-07 20:30 +0200
                Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Lorenzo Stoakes <lstoakes@gmail.com> - 2016-10-10 10:30 +0200
                Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Jan Kara <jack@suse.cz> - 2016-10-10 18:40 +0200
                Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA  balancing Jan Kara <jack@suse.cz> - 2016-10-10 10:40 +0200

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