Re: [PATCH] coredump_filter: enable to change the default filter

Andrew Morton
2008-12-11T23:11:04Z

On Thu, 11 Dec 2008 15:46:49 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> Hi
>
> > This patch introduces new kernel parameter `coredump_filter'.
> > Setting a value to this parameter causes the default bitmask
> > of coredump_filter to be changed.
> >
> > It is useful for users to change coredump_filter settings for
> > the whole system at boot time. Without this parameter, users
> > have to change coredump_filter settings for each /proc/<pid>/
> > in an initializing script.
>
> I think this patch only useful on following situation, right?
>
> - Administrator can't change rc script.
> - Administrator can change boot parameter.
>
>
> When happen above situation?
> or, you intent to init process debugging?

Yes, this can be implemented in userspace by setting init's filter
before init forks any other processes.

I can understand the practical problems with that form of implementation
however :(

Or does the patch change other behaviour? Say, when mm_init() is
called by a kernel thread (current->mm==NULL)? call_usermodehelper(),
for example?

If so, then setting init's filter doesn't cover that case.