Re: [PATCH] [RESEND] rlimits: Print more information when limitsare exceeded

From: David Henningsson
Date: Fri Mar 30 2012 - 10:12:47 EST

On 03/30/2012 03:39 PM, Thomas Gleixner wrote:
On Fri, 24 Feb 2012, Arun Raghavan wrote:

This dumps some information in logs when a process exceeds its CPU or RT
limits (soft and hard). Makes debugging easier when userspace triggers
these limits.

Why do we need to spam the logs with such information?

SIGXCPU is only ever sent by this code. If there is a signal handler
in the application it's easy to debug. If not it's even easier, the
thing will simply be killed and you get the reason printed.

I'm not totally sure, but don't we log SIGSEGVs? If so, the same reasoning would apply to SIGSEGV.

For the SIGKILL case there only a limited number of reasons why a
SIGKILL is sent. So no, I rather commit a patch which removes that
ugly printk which is already there instead of adding more of them.

The reason I proposed some kind of printk for SIGKILL, was to get some diagnostic information out of the SIGKILL. E g, if you have two threads both running on rtprio rlimits in the same process, it would be very interesting to know which one of them was causing the kernel to send SIGKILL.

Also, it could be useful to know whether the SIGKILL was actually sent by the kernel, or by some other process feeling evil (e g "kill -9").

David Henningsson, Canonical Ltd.
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