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Re: [patch] mremap.2: Add description of old_size == 0 functionality

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On 09/15/2017 11:53 PM, Mike Kravetz wrote:
> +If the value of \fIold_size\fP is zero, and \fIold_address\fP refers to
> +a private anonymous mapping, then
> +.BR mremap ()
> +will create a new mapping of the same pages. \fInew_size\fP
> +will be the size of the new mapping and the location of the new mapping
> +may be specified with \fInew_address\fP, see the description of
> +.B MREMAP_FIXED
> +below.  If a new mapping is requested via this method, then the
> +.B MREMAP_MAYMOVE
> +flag must also be specified.  This functionality is deprecated, and no
> +new code should be written to use this feature.  A better method of
> +obtaining multiple mappings of the same private anonymous memory is via the
> +.BR memfd_create()
> +system call.

Is there any particular reason to deprecate this?

In glibc, we cannot use memfd_create and keep the file descriptor around 
because the application can close descriptors beneath us.

(We might want to use alias mappings to avoid run-time code generation 
for PLT-less LD_AUDIT interceptors.)

Thanks,
Florian

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[patch] mremap.2: Add description of old_size == 0 functionality Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-15 23:40 +0200
  Re: [patch] mremap.2: Add description of old_size == 0 functionality Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-16 00:00 +0200
    Re: [patch] mremap.2: Add description of old_size == 0 functionality Florian Weimer <fweimer@redhat.com> - 2017-09-18 15:50 +0200
      Re: [patch] mremap.2: Add description of old_size == 0 functionality Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-18 19:20 +0200
        Re: [patch] mremap.2: Add description of old_size == 0 functionality Florian Weimer <fweimer@redhat.com> - 2017-09-19 14:20 +0200
          [patch v2] mremap.2: Add description of old_size == 0 functionality Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-19 23:50 +0200
            Re: [patch v2] mremap.2: Add description of old_size == 0  functionality "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-09-20 09:30 +0200
              Re: [patch v2] mremap.2: Add description of old_size == 0  functionality Michal Hocko <mhocko@kernel.org> - 2017-09-25 14:40 +0200
                Re: [patch v2] mremap.2: Add description of old_size == 0 functionality "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-09-25 14:50 +0200
              Re: [patch v2] mremap.2: Add description of old_size == 0  functionality Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-25 18:40 +0200
                Re: [patch v2] mremap.2: Add description of old_size == 0 functionality "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-09-25 21:30 +0200
          Re: [patch] mremap.2: Add description of old_size == 0 functionality Michal Hocko <mhocko@kernel.org> - 2017-09-25 14:40 +0200
            Re: [patch] mremap.2: Add description of old_size == 0 functionality Florian Weimer <fweimer@redhat.com> - 2017-09-25 14:50 +0200
              Re: [patch] mremap.2: Add description of old_size == 0 functionality Michal Hocko <mhocko@kernel.org> - 2017-09-25 15:00 +0200
                Re: [patch] mremap.2: Add description of old_size == 0 functionality Florian Weimer <fweimer@redhat.com> - 2017-09-25 15:20 +0200
                Re: [patch] mremap.2: Add description of old_size == 0 functionality Michal Hocko <mhocko@kernel.org> - 2017-09-25 17:00 +0200
                Re: [patch] mremap.2: Add description of old_size == 0 functionality Florian Weimer <fweimer@redhat.com> - 2017-09-25 17:00 +0200
  Re: [patch] mremap.2: Add description of old_size == 0 functionality Jann Horn <jannh@google.com> - 2017-09-18 04:00 +0200
    Re: [patch] mremap.2: Add description of old_size == 0 functionality Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-18 19:30 +0200

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