linux-kernel - Re: [PATCH v2] cpufreq: powernv: fix stack bloat and NR

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Date:   Mon, 28 Oct 2019 16:26:16 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     John Hubbard <jhubbard@...dia.com>,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
        linux-pm@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2] cpufreq: powernv: fix stack bloat and NR_CPUS limitation

On Friday, October 18, 2019 7:07:12 AM CET Viresh Kumar wrote:
> On 17-10-19, 21:55, John Hubbard wrote:
> > The following build warning occurred on powerpc 64-bit builds:
> > 
> > drivers/cpufreq/powernv-cpufreq.c: In function 'init_chip_info':
> > drivers/cpufreq/powernv-cpufreq.c:1070:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]
> > 
> > This is due to putting 1024 bytes on the stack:
> > 
> >     unsigned int chip[256];
> > 
> > ...and while looking at this, it also has a bug: it fails with a stack
> > overrun, if CONFIG_NR_CPUS > 256.
> > 
> > Fix both problems by dynamically allocating based on CONFIG_NR_CPUS.
> > 
> > Fixes: 053819e0bf840 ("cpufreq: powernv: Handle throttling due to Pmax capping at chip level")
> > Cc: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
> > Cc: Preeti U Murthy <preeti@...ux.vnet.ibm.com>
> > Cc: Viresh Kumar <viresh.kumar@...aro.org>
> > Cc: Rafael J. Wysocki <rjw@...ysocki.net>
> > Cc: linux-pm@...r.kernel.org
> > Cc: linuxppc-dev@...ts.ozlabs.org
> > Signed-off-by: John Hubbard <jhubbard@...dia.com>
> > ---
> > 
> > Changes since v1: includes Viresh's review commit fixes.
> > 
> >  drivers/cpufreq/powernv-cpufreq.c | 17 +++++++++++++----
> >  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> 
> 

Applying as 5.5 material, thanks!