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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>,
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Subject: Re: Random panic in load_balance() with 3.16-rc
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From: fche@redhat.com (Frank Ch. Eigler)
Date: Mon, 28 Jul 2014 08:26:59 -0400
In-Reply-To: <CA+55aFyCh8B4kuc66_+wr8eM+kP7-hJ9utdtpLih661Xf8YGgQ@mail.gmail.com> (Linus Torvalds's message of "Sat, 26 Jul 2014 13:39:54 -0700")
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torvalds wrote:

> [...]
> Actually, I prefer my patch that did it with cc-option checking, and
> does it unconditionally.
>
> Because if we do it even for non-debug builds - where it ostensibly
> shouldn't matter - we then have that GCC_COMPARE_DEBUG thing working
> regardless of configuration.

Please note that the data produced by "-g -fvar-tracking" is consumed
by tools like systemtap, perf, crash, and makes a significant
difference to the observability of debug AND non-debug kernels.  (The
presence of compiled-in DEBUG_* self-checking code is orthogonal to
kernel observability via debuginfo.)  Please consider only disabling
var-tracking optionally/temporarily to work around this already-fixed
compiler bug, but not losing high-quality dwarf data permanently.

- FChE