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Date: Thu, 20 Oct 2016 18:50:28 -0400
From: Dave Jones <davej@codemonkey.org.uk>
To: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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On Tue, Oct 18, 2016 at 06:05:57PM -0700, Andy Lutomirski wrote:

 > One possible debugging approach would be to change:
 > 
 > #define NR_CACHED_STACKS 2
 > 
 > to
 > 
 > #define NR_CACHED_STACKS 0
 > 
 > in kernel/fork.c and to set CONFIG_DEBUG_PAGEALLOC=y.  The latter will 
 > force an immediate TLB flush after vfree.

I can give that idea some runtime, but it sounds like this a case where
we're trying to prove a negative, and that'll just run and run ? In which case I
might do this when I'm travelling on Sunday.

 > Also, CONFIG_DEBUG_VIRTUAL=y can be quite helpful for debugging stack 
 > issues.  I'm tempted to do something equivalent to hardwiring that 
 > option on for a while if CONFIG_VMAP_STACK=y.

This one I had on. Nothing interesting jumped out.

	Dave