linux-kernel - RE: [PATCH v2 5/5] printk/nmi: Increase the size of the temporary buffer

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Date:	Wed, 2 Dec 2015 16:20:41 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'yalin wang' <yalin.wang2010@...il.com>,
	Petr Mladek <pmladek@...e.com>
CC:	"linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
	Daniel Thompson <daniel.thompson@...aro.org>,
	Jiri Kosina <jkosina@...e.com>,
	"linux-cris-kernel@...s.com" <linux-cris-kernel@...s.com>,
	"linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"x86@...nel.org" <x86@...nel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"adi-buildroot-devel@...ts.sourceforge.net" 
	<adi-buildroot-devel@...ts.sourceforge.net>,
	Ingo Molnar <mingo@...hat.com>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	"sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v2 5/5] printk/nmi: Increase the size of the temporary
 buffer

From: yalin wang
> Sent: 30 November 2015 16:42
> > On Nov 27, 2015, at 19:09, Petr Mladek <pmladek@...e.com> wrote:
> >
> > Testing has shown that the backtrace sometimes does not fit
> > into the 4kB temporary buffer that is used in NMI context.
> >
> > The warnings are gone when I double the temporary buffer size.

You are wasting a lot of memory for something that is infrequently used.
There ought to be some way of copying partial tracebacks into the
main buffer.

	David