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SubjectRe: + core_pattern-set-core-helpers-root-and-namespace-to-crashing-process .patch added to -mm tree
On Tue, Dec 18, 2012 at 12:45:18PM -0800, Eric W. Biederman wrote:
> Neil Horman <nhorman@tuxdriver.com> writes:
>
> > On Tue, Dec 18, 2012 at 09:06:04PM +0100, Oleg Nesterov wrote:
> >> On 12/17, Neil Horman wrote:
> >> >
> >> > On Mon, Dec 17, 2012 at 05:04:08PM +0100, Oleg Nesterov wrote:
> >> > >
> >> > > > Is there a way to switch all namespaces, except for the pid
> >> > > > namespace?
> >> > >
> >> > > Which exactly namespaces you want to change?
> >> > >
> >> > Ideally, I want the pipe reader process to execute in the same namespaces that
> >> > the crashing process executed in (i.e. the pipe reader should execute as though
> >> > the crashing process forked it).
> >>
> >> Yes, and we probably want to change pid_ns as well. But afaics currently
> >> this is not possible, even setns can't do this.
>
> The code for setns to change the pid namespace just merged.
>
Can you post a link to the merge commit for reference so I can take a look at
it?

> Oleg I copied you on that code when I put it up for review. Did I use
> the wrong email address?
>
> >> BTW. Of course this is subjective, but personally I think that "||"
> >> looks strange. Perhaps it would be better to add something like
> >> --croot argument?
> >>
> > The || is ambiguous with its simmilarity to a shell 'or' command, but I don't
> > think the --croot argument is much better on that front, as that then becomes
> > ambiguous with arguments supplied to the pipe reader directly. The token should
> > be leading the pipe_reader string in core_pattern to indicate a change in
> > environment independent of the executable path. Perhaps |^ or something
> > simmilar?
>
> I failed to send my earlier reply but there is another problem with the
> approach of only having one global core dump pattern. You can't set it
> per container. Which means a special character to switch namespeces
> while a reasonable solution (and arguably unnecessary solution) is not a
> complete solution.
>
> > Either way, Andrew, could you please drop this patch? Olegs comments I think
> > make it pretty clear I've got some more work to do on this.
>
> If we just want one pattern we should be able to to robustly implement
> this in userspace with the existing functionality. With the caveat that
> we need to get some pid namespace and user namespace bugs in the core
> pattern generation fixed. But we need to fix those bugs anyway.
>
Then perhaps the right thing to do here is in fact just make core_pattern a
per-namespace sysctl. I only took a brief look, but I was unable to find an
example of such a per-namespace systctl. Do we already have the infrastructure
to do such a thing? I didn't think we did.

Thanks!
Neil

> Eric
>


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