From: Alexey Izbyshev <firstname.lastname@example.org>
Cc: Florian Weimer <email@example.com>,
Rich Felker <firstname.lastname@example.org>, Andrei Vagin <email@example.com>,
Christian Brauner <firstname.lastname@example.org>
Subject: Re: [musl] vfork()-based posix_spawn() has more failure modes than fork()-based one
Date: Tue, 03 May 2022 00:49:16 +0300 [thread overview]
Message-ID: <email@example.com> (raw)
On 2022-05-03 00:31, Carlos O'Donell wrote:
> On 5/2/22 17:25, Florian Weimer wrote:
>> * Rich Felker:
>>> I'm trying to understand how this comes to be. The child should
>>> inherit the namespaces of the parent and thus should not be in a
>>> different namespace that precludes spawn. I'm guessing this is some
>>> oddity where unshare doesn't affect the process itself, only its
>>> children? If so, it seems like a bug that it doesn't affect the
>>> process itself after execve (after unshare(1) runs your test
>>> but that probably can't be fixed now on the Linux side for stability
>>> reasons. :(
>> It's about fundamentally conflicting requirements.
>> The vDSO data mapping needs to store the time offset, so it has to be
>> distinct from the original namespace. vfork preserves the VM sharing.
>> It's not possible to do both things at the same time.
>> unshare(CLONE_NEWTIME) should have been specified to only take effect
>> after execve, when the vDSO is remapped anyway.
> Can we ask some kernel developers for an opinion?
Christian Brauner had some comments [1,2] on this. Time namespaces were
added in  by Andrei Vagin. Adding both to CC.
next prev parent reply other threads:[~2022-05-02 21:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-02 19:26 Alexey Izbyshev
2022-05-02 20:49 ` Carlos O'Donell
2022-05-02 21:18 ` Rich Felker
2022-05-02 21:25 ` Florian Weimer
2022-05-02 21:31 ` Rich Felker
2023-02-22 22:04 ` Alexey Izbyshev
2022-05-02 21:31 ` Carlos O'Donell
2022-05-02 21:49 ` Alexey Izbyshev [this message]
2022-05-02 21:56 ` Alexey Izbyshev
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