lkml.org 
[lkml]   [2008]   [Apr]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2.6.25-mm1: not looking good

* Jason Wessel <jason.wessel@windriver.com> wrote:

> > [...] The final initcall is init_kgdbts() and disabling KGDB
> > prevents the hang.

> That enables verbose logging of exactly what is going on and will show
> where wheels fall off the cart. If the kernel is dying silently it
> means the early exception code has completely failed in some way on
> the kernel architecture that was selected, and of course the .config
> is always useful in this case.

incidentally, just today, in overnight testing i triggered a similar
hang in the KGDB self-test:

http://redhat.com/~mingo/misc/config-Thu_Apr_17_23_46_36_CEST_2008.bad

to get a similar tree to the one i tested, pick up sched-devel/latest
from:

http://people.redhat.com/mingo/sched-devel.git/README

pick up that failing .config, do 'make oldconfig' and accept all the
defaults to get a comparable kernel to mine. (kgdb is embedded in
sched-devel.git.)

the hang was at:

[ 12.504057] Calling initcall 0xffffffff80b800c1: init_kgdbts+0x0/0x1b()
[ 12.511298] kgdb: Registered I/O driver kgdbts.
[ 12.515062] kgdbts:RUN plant and detach test
[ 12.520283] kgdbts:RUN sw breakpoint test
[ 12.524651] kgdbts:RUN bad memory access test
[ 12.529052] kgdbts:RUN singlestep breakpoint test

full log:

http://redhat.com/~mingo/misc/log-Thu_Apr_17_23_46_36_CEST_2008.bad

note that this was a 64-bit config too - our tests do a perfect mix of
50% 32-bit and 50% 64-bit kernels. So single-stepping of the kernel
broke in some circumstances.

find the boot log below. (it also includes all command line parameters)

This is the first time ever i saw the self-test in KGDB hanging, so it's
some recent non-KGDB change that provoked it or made it more likely. The
KGDB self-test runs very frequently in my bootup tests:

[ 12.508236] kgdb: Registered I/O driver kgdbts.
[ 12.511245] kgdbts:RUN plant and detach test
[ 12.517418] kgdbts:RUN sw breakpoint test
[ 12.521056] kgdbts:RUN bad memory access test
[ 12.525515] kgdbts:RUN singlestep breakpoint test
[ 12.531483] kgdbts:RUN hw breakpoint test
[ 12.536142] kgdbts:RUN hw write breakpoint test
[ 12.541007] kgdbts:RUN access write breakpoint test
[ 12.546223] kgdbts:RUN do_fork for 100 breakpoints

so the latest kgdb-light tree literally survived thousands of such tests
since it was changed last.

unfortunately, the condition was not reproducible - i booted it once
more and then it came up just fine - using the same bzImage.

there's no recent change in x86.git related to the TF flag that i could
think of to cause something like this. I checked changes to traps_64.c
and entry_64.S, and nothing suspicious.

Ingo


\
 
 \ /
  Last update: 2008-04-18 09:41    [W:0.141 / U:1.140 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site