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Re: static TLS exhausted on ppc64le

On 30/09/2019 15:22, Rich Felker wrote:
> On Mon, Sep 30, 2019 at 02:14:46PM +0000, Szabolcs Nagy wrote:
>> On 30/09/2019 15:02, Dan Horák wrote:
>>> Hi,
>>> I would like to open a problem we have already met twice in Fedora. the
>>> symptom is
>>> "/lib64/ cannot allocate memory in static TLS block"
>>> usually when loading a lot of libraries/modules into a Python
>>> application. It happened on ppc64le and also on aarch64 systems.
>>> We have 2 reports in Fedora bugzilla about with more details.
>>> We have already discussed that briefly with Florian and other members of
>>> the Red Hat toolchain team, but outcome was in form of a recommendation
>>> to reduce the usage of "static TLS" objects in the individual libraries.
>>> But the open question still is - is there a fix for the TLS space
>>> exhaustion? I believe it can easily become a more serious problem soon.
>> (a workaround is preloading the problematic libs at startup time)
>> i think it's a bug in, gcc should not build
>> broken dsos by default (unless it can ensure they are never
>> loaded dynamically):
>> (libitm has a similar hack)
>> e.g. this is patched out manually when building a musl libc
>> based toolchain since musl does not reserve static tls for
>> broken dsos.
>> i would support removing such hacks from gcc target libs
>> (or at least hide it behind some obscure config option),
>> but i guess that should be discussed with gcc maintainers
>> and not on libc-alpha.
> I'm strongly in favor of such a change. I'd also like to propose that
> glibc deprecate dlopen of libraries with initial-exec access to their
> own TLS and set an EOL for it. While the GCC stuff can be fixed
> without doing that, GPU vendors are going to keep doing this until
> it's hard-breaking.

created gcc bug

note: the aarch64 and powerpc64 only failures can
be fixed in glibc, but i'd prefer to fix this in gcc.

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