Bug involving dynamic_debug and '-p' modifier

From: Andrew Cooks
Date: Mon Mar 11 2013 - 21:14:11 EST


Hi Jason

When I specify a '-p' modifier in the dynamic debug options in the
kernel command line, I get a kernel panic during boot. The panic
happens after userspace starts doing graphical stuff, but I haven't
been able to pinpoint exactly what.

If I use '=_' instead of '-p', or boot to a recovery mode, or change
the modifier after booting using debugfs, the panic doesn't occur. For
example, booting to runlevel 3 with '=_', then flipping the same
modifier to first to '+p' and then to '-p', before starting X does not
result in a panic.

Booting to runlevel 3 (or even 1!), with '-p' results in a panic, but
'rdshell' is OK.

I also tried the Red Hat kernel (just because it's installed - I
haven't figured out how to tell the package manager that I don't want
a kernel). This also panics, but it says that '-p' is not supported.

Please let me know if you need me to do any other tests.

'-p', panic: http://pastebin.com/8yAcBQdY
'-p', rdshell, no panic: http://pastebin.com/Hi2a7BZA

--
a.
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