[REGRESSION] RLIMIT_DATA crashes named

From	Laura Abbott <labbott@redhat.com>
Newsgroups	linux.kernel
Subject	[REGRESSION] RLIMIT_DATA crashes named
Date	2016-09-16 17:20 +0200
Message-ID	<si35L-6q0-15@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hi,

Fedora received a bug report[1] after pushing 4.7.2 that named
was segfaulting with named-chroot. With some help (thank you
tibbs!), it was noted that on older kernels named was spitting
out

mmap: named (671): VmData 27566080 exceed data ulimit 23068672.
Will be forbidden soon.

and with f4fcd55841fc ("mm: enable RLIMIT_DATA by default with
workaround for valgrind") it now spits out

mmap: named (593): VmData 27566080 exceed data ulimit 20971520.
Update limits or use boot option ignore_rlimit_data.

Apparently the segfault goes away when dropping datasize=size.
I haven't looked into the named code yet but what I'm
suspecting is named is not setting its limits correctly and
then corrupting itself. This may have existed for much longer
but the rlimit is only now exposing it.

I'd like to propose reverting f4fcd55841fc ("mm: enable RLIMIT_DATA
by default with workaround for valgrind") or default to setting
ignore_rlimit_data to true and spitting out a warning until
named can be fixed.

Thanks,
Laura


[1] https://bugzilla.redhat.com/show_bug.cgi?id=1374917

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[REGRESSION] RLIMIT_DATA crashes named Laura Abbott <labbott@redhat.com> - 2016-09-16 17:20 +0200
  Re: [REGRESSION] RLIMIT_DATA crashes named Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-16 19:50 +0200
    Re: [REGRESSION] RLIMIT_DATA crashes named Laura Abbott <labbott@redhat.com> - 2016-09-16 22:20 +0200
      Re: [REGRESSION] RLIMIT_DATA crashes named Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-16 22:40 +0200
        Re: [REGRESSION] RLIMIT_DATA crashes named Sam Varshavchik <mrsam@courier-mta.com> - 2016-09-17 00:40 +0200
          Re: [REGRESSION] RLIMIT_DATA crashes named Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-17 02:00 +0200
            Re: [REGRESSION] RLIMIT_DATA crashes named Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-17 02:10 +0200
              Re: [REGRESSION] RLIMIT_DATA crashes named Joe Perches <joe@perches.com> - 2016-09-17 06:10 +0200
                Re: [REGRESSION] RLIMIT_DATA crashes named Konstantin Khlebnikov <koct9i@gmail.com> - 2016-09-17 10:40 +0200
                Re: [REGRESSION] RLIMIT_DATA crashes named Cyrill Gorcunov <gorcunov@gmail.com> - 2016-09-17 11:20 +0200
                Re: [REGRESSION] RLIMIT_DATA crashes named Konstantin Khlebnikov <koct9i@gmail.com> - 2016-09-17 14:10 +0200
                Re: [REGRESSION] RLIMIT_DATA crashes named Cyrill Gorcunov <gorcunov@gmail.com> - 2016-09-17 14:30 +0200
                Re: [REGRESSION] RLIMIT_DATA crashes named Konstantin Khlebnikov <koct9i@gmail.com> - 2016-09-17 23:50 +0200
                Re: [REGRESSION] RLIMIT_DATA crashes named Joe Perches <joe@perches.com> - 2016-09-18 00:00 +0200

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