From: Adam Tkac <vonsch@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Palfrader <weasel@debian.org>,
linux-kernel@vger.kernel.org, debian-admin@lists.debian.org,
team@security.debian.org, libpam-modules@packages.debian.org,
stable@kernel.org
Subject: Re: 2.6.28, rlimits, performance and debian etch
Date: Mon, 2 Feb 2009 17:20:00 +0100 [thread overview]
Message-ID: <20090202162000.GA3050@evileye.atkac.englab.brq.redhat.com> (raw)
In-Reply-To: <20090129100509.6969970f.akpm@linux-foundation.org>
On Thu, Jan 29, 2009 at 10:05:09AM -0800, Andrew Morton wrote:
> On Thu, 29 Jan 2009 13:19:00 +0100 Adam Tkac <vonsch@gmail.com> wrote:
>
> >
> > Hi all,
> >
> > I don't think the "rlim_infinity" patch should be reverted. Let me try
> > to explain why.
> >
> > First, code which sets limits to RLIM_INFINITY is very bad idea and
> > that code is Debian specific. I downloaded original pam 0.79 (stripped):
> >
> > for(i = 0; i < RLIM_NLIMITS; i++) {
> > ...
> > int r = getrlimit(i, &pl->limits[i].limit);
> > ...
> >
> > as you can see original pam sets limits to inherited defaults. After
> > code written above Debian adds their patch:
> >
> > if (limits_not_defined_in_limits_conf) {
> > ...
> > case RLIMIT_NOFILE:
> > ...
> > pl->limits[i].limit.rlim_cur = RLIM_INFINITY;
> > pl->limits[i].limit.rlim_max = RLIM_INFINITY;
> > ...
> > }
> >
> > so as you can see inherited default limits are overriden to infinity.
> > In my opinion Debian should revert their patch which is, at least,
> > pretty incorrect and unsecure.
> >
> > Next argument is POSIX compatibility (from setrlimit() specification):
> >
> > "The value RLIM_INFINITY, defined in <sys/resource.h>, shall be
> > considered to be larger than any other limit value. If a call to
> > getrlimit() returns RLIM_INFINITY for a resource, it means the
> > implementation shall not enforce limits on that resource. Specifying
> > RLIM_INFINITY as any resource limit value on a successful call to
> > setrlimit() shall inhibit enforcement of that resource limit."
> >
> > So kernel does what is expected. If you want "unlimited" number of
> > descriptors, you have it.
> >
> > Please consider again where exactly problem is, if in Debian patch or
> > in kernel patch. From my point of view Debian patch should be
> > reverted, not the kernel one.
> >
>
> Sure, debian might well be wrong. But the bottom line is that the
> kernel changed, and people's machines broke.
>
> If the kernel change was really really important then we might just
> grit our teeth and live with the breakage. But this change _wasn't_ a
> terribly important one. So I think we should back it out while we find
> another way of implementing it which does not break currently deployed
> installations.
Well, if we should fix Debian's problem I think better would be to set
limit of files to reasonable number instead of sysctl_nr_open (for
example 4096 or 8192).
Adam
next prev parent reply other threads:[~2009-02-02 16:20 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-21 11:52 2.6.28, rlimits, performance and debian etch Peter Palfrader
2009-01-23 21:07 ` Florian Weimer
2009-01-23 22:02 ` David Daney
2009-01-23 23:11 ` Peter Palfrader
2009-01-25 10:59 ` Florian Weimer
2009-01-27 23:17 ` Andrew Morton
2009-01-29 12:19 ` Adam Tkac
2009-01-29 18:05 ` Andrew Morton
2009-01-29 18:10 ` Peter Palfrader
2009-02-02 16:20 ` Adam Tkac [this message]
2009-02-08 22:31 ` Steve Langasek
2009-02-26 21:48 Frans Pop
2009-02-26 22:01 ` Steve Langasek
2009-02-27 7:30 ` Peter Palfrader
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