Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone

From	Andrea Arcangeli <aarcange@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone
Date	2017-08-02 18:50 +0200
Message-ID	<ua50l-3TJ-1@gated-at.bofh.it> (permalink)
References	(2 earlier) <u9j5n-6QC-1@gated-at.bofh.it> <u9jf3-6U3-1@gated-at.bofh.it> <ua16q-1sn-21@gated-at.bofh.it> <ua4dX-3lq-1@gated-at.bofh.it> <ua4GZ-3M5-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Wed, Aug 02, 2017 at 06:22:49PM +0200, Michal Hocko wrote:
> ESRCH refers to "no such process". Strictly speaking userfaultfd code is
> about a mm which is gone but that is a mere detail. In fact the owner of

Well this whole issue about which retval, is about a mere detail in
the first place, so I don't think you can discount all other mere
details as irrelevant in the evaluation of a change to solve a mere
detail.

> But as I've said, this might be really risky to change. My impression
> was that userfaultfd is not widely used yet and those can be fixed
> easily but if that is not the case then we have to live with the current
> ENOSPC.

The only change would be for userfaultfd non cooperative mode, and
CRIU is the main user of that. So I think it is up to Mike to decide,
I'm fine either ways. I certainly agree ESRCH could be a slightly
better fit, I only wanted to clarify it's not a 100% match either.

Thread

Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Andrea Arcangeli <aarcange@redhat.com> - 2017-07-31 15:40 +0200
  Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Michal Hocko <mhocko@kernel.org> - 2017-07-31 15:50 +0200
    Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Mike Rapoport <rppt@linux.vnet.ibm.com> - 2017-08-02 14:40 +0200
      Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone "Dr. David Alan Gilbert" <dgilbert@redhat.com> - 2017-08-02 15:30 +0200
      Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Andrea Arcangeli <aarcange@redhat.com> - 2017-08-02 18:00 +0200
        Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Michal Hocko <mhocko@kernel.org> - 2017-08-02 18:30 +0200
          Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Andrea Arcangeli <aarcange@redhat.com> - 2017-08-02 18:50 +0200
            Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Mike Rapoport <rppt@linux.vnet.ibm.com> - 2017-08-03 19:30 +0200
              Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Andrea Arcangeli <aarcange@redhat.com> - 2017-08-03 23:30 +0200

csiph-web