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Date: Mon, 19 Dec 2016 18:25:49 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Martin Steigerwald <martin.steigerwald@teamix.de>
Cc: Ingo Molnar <mingo@kernel.org>, Andrew Morton <akpm@osdl.org>,
        Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
        Nicolas Dichtel <nicolas.dichtel@6wind.com>,
        Jay Lan <jlan@engr.sgi.com>, Martin Steigerwald <martin@lichtvoll.de>,
        Gerlof Langeveld <gerlof.langeveld@atoptool.nl>,
        Marc Haber <mh+debian-packages@zugschlus.de>,
        Ben Hutchings <ben@decadent.org.uk>,
        Balbir Singh <bsingharora@gmail.com>, Tejun Heo <tj@kernel.org>
Subject: Re: [REGRESSION] Two issues that prevent process accounting
 (taskstats) from working correctly
Message-ID: <20161219172549.GK3107@twins.programming.kicks-ass.net>
References: <5967400.cFS0L5jxeH@merkaba>
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On Mon, Dec 19, 2016 at 01:06:00PM +0100, Martin Steigerwald wrote:
> 
> 2) When using the NETLINK inface, the command TASKSTATS_CMD_GET 
> consequently returns -EINVAL.
> 
> The code that is used by the atopacctd daemon is based on the demo code 
> 'getdelays.c' that can be found in the kernel source code tree
> (..../linux/Documentation/accounting/getdelays.c). Also this 'getdelays' 
> program does not work any more (also -EINVAL on the same call)
> with the newer kernels. I really spent a lot of time on this issue to 
> get the code running (there are many places in the kernel code where
> -EINVAL for this call can be given), but I did not succeed. It is really 
> an incompatibility introduced by the kernel code.
> It would be nice if the kernel maintainers provide a working version of 
> the getdelays program in the kernel source tree.
> 
> I only experience this problem on Debian8 with a 4.8 kernel (virtual 
> machine with 4 cores).
> On CentOS7 with a 4.8 kernel it works fine (physical machine with 4 cores).
> 
> I will anyhow adapt atopacctd for this issue that it detects and logs 
> the -EINVAL and terminates.
> The current version of atopacctd keeps running which is not useful at all.
> 
> 
> I reported this as:
> 
> Bug 190711 - Process accounting: Using the NETLINK inface, the command 
> TASKSTATS_CMD_GET returns -EINVAL
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=190711


Ben Hutchings reports:

"It looks like the taskstats bug was introduced by 513e3d2d11c9 as that
means cpumask_parse() may not initialise as many bits as
cpumask_subset() compares"