From: Tim Hockin <thockin@hockin.org>
To: Nick Piggin <piggin@cyberone.com.au>
Cc: Rusty Russell <rusty@au1.ibm.com>,
vatsa@in.ibm.com, linux-kernel@vger.kernel.org,
torvalds@osdl.org, akpm@osdl.org, rml@tech9.net
Subject: Re: CPU Hotplug: Hotplug Script And SIGPWR
Date: Tue, 20 Jan 2004 00:29:43 -0800 [thread overview]
Message-ID: <20040120082943.GA15733@hockin.org> (raw)
In-Reply-To: <400CE354.8060300@cyberone.com.au>
On Tue, Jan 20, 2004 at 07:14:12PM +1100, Nick Piggin wrote:
> >Under what conditions? Not arbitrary entropy, surely. If a hotplug script
> >is present and does not blow up, it should be safe to assume it will be run
> >upon an event being delivered. If not, we have a WAY bigger problem :)
> >
>
> That assumption is not safe. The main problems are of course process limits
> and memory allocation failure.
If root has a process limit that make hotplug scripts fail to run, then
we're hosed in a lot of ways. And if we fail to allocate memory, there
really ought to be some retry or something. It seems to me that a failure
to run a hotplug script is a BAD THING.
> >Sending it a SIGPWR means you have to run it on a different CPU that it was
> >affined to, which is already a violation.
>
> At least the task has the option to handle the problem.
But it is a violation of the affinity. As the kernel we CAN NOT know what
the affinity really means. Maybe there is some way for a task to indicate
it would like to receive SIGPWR in that case. Or some other signal. Can we
invent new signals?
That way a task that KNOWS about the CPU disappearing underneath it can be
wise, while everything else will not just get killed.
next prev parent reply other threads:[~2004-01-20 8:29 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20040116174446.A2820@in.ibm.com>
2004-01-20 5:44 ` CPU Hotplug: Hotplug Script And SIGPWR Rusty Russell
2004-01-20 6:33 ` Tim Hockin
2004-01-20 6:43 ` Nick Piggin
2004-01-20 6:52 ` Tim Hockin
2004-01-20 7:11 ` Nick Piggin
2004-01-20 7:30 ` Tim Hockin
2004-01-20 7:45 ` Nick Piggin
2004-01-20 7:54 ` Tim Hockin
2004-01-20 8:14 ` Nick Piggin
2004-01-20 8:29 ` Tim Hockin [this message]
2004-01-20 8:37 ` Nick Piggin
2004-01-20 8:43 ` Tim Hockin
2004-01-21 4:06 ` Srivatsa Vaddagiri
2004-01-21 4:14 ` Nick Piggin
2004-01-21 5:09 ` Srivatsa Vaddagiri
2004-01-21 7:08 ` Tim Hockin
2004-01-21 15:07 ` Matthias Urlichs
2004-01-22 5:29 ` Rusty Russell
2004-01-21 7:09 ` Tim Hockin
2004-01-21 7:31 ` Nick Piggin
2004-01-21 7:42 ` Tim Hockin
2004-01-21 8:11 ` Rusty Russell
2004-01-21 5:07 ` Rusty Russell
2004-01-20 8:41 ` Stefan Smietanowski
2004-01-20 8:49 ` Nick Piggin
2004-01-20 9:12 ` Tim Hockin
2004-01-21 0:00 ` Rusty Russell
2004-01-20 23:51 ` Rusty Russell
2004-01-20 7:45 ` Rusty Russell
2004-01-20 8:37 ` Tim Hockin
2004-01-20 9:29 ` Srivatsa Vaddagiri
2004-01-21 0:12 ` Rusty Russell
[not found] <fa.f37o48p.1io5q5@ifi.uio.no>
[not found] ` <fa.frjqvfo.170g8hq@ifi.uio.no>
2004-01-20 17:49 ` Andy Lutomirski
2004-01-21 4:33 ` Rusty Russell
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