linux-kernel - Re: [RESEND 2] [PATCH] rlimits: Print more information when limits are exceeded

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Date:   Sat, 18 Feb 2017 21:17:10 +0530
From:   Arun Raghavan <arun@...nraghavan.net>
To:     Arun Raghavan <arun@...nraghavan.net>, linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RESEND 2] [PATCH] rlimits: Print more information when limits are
 exceeded



On Sat, 18 Feb 2017, at 02:07 PM, 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.
> 
> Signed-off-by: Arun Raghavan <arun@...nraghavan.net>
> ---
>  kernel/time/posix-cpu-timers.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> Hello,
> This has come up a couple of times in the past, but we haven't been able
> to
> resolve whatever issues were pointed out.
> 
> In the mean time, we have frustrated users who don't know where they're
> getting
> a SIGKILL from, and I'd really like to have a way for people to not have
> to go
> through this.
> 
> The issues that came up the last time were:
> 
>  1. SIGXCPU messages shouldn't be needed since they can be caught: it's
>  still
>     useful to have the log because it isn't always possible to pin down
>     the
>     thread causing the problem in userspace.
> 
>  2. SIGKILL logging should be centralised: there seem to be multiple
>  paths that
>     trigger a SIGKILL -- and it seemed a bit ugly to try to add a reason
>     parameter on all of them for the KILL case. Any other suggestions on
>     how to
>     deal with this?
> 
> I'm happy to fix this up to actually make it this time, but if there
> aren't
> none, just pushing this out will make our lives a little less painful.

That was meant to read -- "... if there aren't blocking objections to
this, just pushing this out will make our lives a little less painful."

-- Arun