Re: libc recently more aggressive about pthread locks in stable ?
On 11/05/2016 08:13 PM, Ian Jackson wrote:
> I have just been debugging a ghostscript segfault on jessie amd64.
>
> Looking at the code, I think that gs in jessie is plainly violating
> the rules about the use of pthread locks. On my partner's machine,
> this makes it segfault on termination (with some input files, at
> least). On my machine it works just fine. The code in sid is better.
>
> I recently encountered what seems to be a similar bug in ogg123 in
> stable. #842796.
>
> Has something changed in jessie's libc recently ? I find it difficult
> to imagine that these bugs would have been missed earlier during the
> life of jessie.
Recently Frank Fegert discovered a problem with locking in open-iscsi
that only occurs on new hardware. The code previously was wrong, but
earlier CPUs were more forgiving when it came to this error and it
couldn't be triggered.
Frank wrote about the problem in his blog in great detail:
http://www.bityard.org/blog/2016/08/05/debugging_segfaults_open-iscsi_iscsiuio_intel_broadwell
I haven't looked in detail at your problem, but I could easily
imagine that the problem you're experiencing with other packages is
similar, especially since you mentioned migrating to new hardware.
Hope that helps.
Regards,
Christian
PS: In case someone was wondering: the specific problem with
open-iscsi is now fixed in sid, testing and jessie-backports; jessie
is not affected because we didn't yet build the component with the
issue there.
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