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Date: Fri, 30 May 2014 10:21:13 +1000
From: Dave Chinner <david@fromorbit.com>
To: Dave Jones <davej@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jens Axboe <axboe@kernel.dk>, Minchan Kim <minchan@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, Mel Gorman <mgorman@suse.de>,
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        Hugh Dickins <hughd@google.com>, Rusty Russell <rusty@rustcorp.com.au>,
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        Dave Hansen <dave.hansen@intel.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC 2/2] x86_64: expand kernel stack to 16K
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On Thu, May 29, 2014 at 08:06:49PM -0400, Dave Jones wrote:
> On Fri, May 30, 2014 at 09:53:08AM +1000, Dave Chinner wrote:
> 
>  > That sounds like a plan. Perhaps it would be useful to add a
>  > WARN_ON_ONCE(stack_usage > 8k) (or some other arbitrary depth beyond
>  > 8k) so that we get some indication that we're hitting a deep stack
>  > but the system otherwise keeps functioning. That gives us some
>  > motivation to keep stack usage down but isn't a fatal problem like
>  > it is now....
> 
> We have check_stack_usage() and DEBUG_STACK_USAGE for this.
> Though it needs some tweaking if we move to 16K

Right, but it doesn't throw loud warnings when a specific threshold
is reached - it just issues a quiet message when a process exits
telling you what the maximum was without giving us a stack to chew
on....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com