Re: Early drop to debugger with DEBUG_MEMGUARD

On Mon, Aug 12, 2013 at 09:10:55AM -0700, Davide Italiano wrote:
> ...
> OK, I'm not sure I can make an immediate guess on where's the problem
> now (without access to my main workstation), so I think you need to
> wait tomorrow unless someone beats me to the punch. The best I can say
> is that maybe r254025 is responsible for this. Try to revert and see
> if things work again.
> ....

I tried backing out r254025, but there had been enough time that other
commits had touched the same files.  Ended up backing out r254165,
r254171, r254172, and r254182 as well (which seemed to go OK), but the
result didn't build.

So I just checked out a new src working copy _at_r254024, built the world
and kernel cleanly, verified that it booted OK, then updated the src
working copy to r254025, built, booted, and ... BANG!

Booting...
GDB: no debug ports present
KDB: debugger backends: ddb
KDB: current backend: ddb
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FreeBSD 10.0-CURRENT #3  r254025M/254025:1000041: Mon Aug 12 14:23:48 PDT 2013
    root_at_freebeast.catwhisker.org:/common/S3/obj/usr/src/sys/MEMGUARD i386
FreeBSD clang version 3.3 (tags/RELEASE_33/final 183502) 20130610
WARNING: WITNESS option enabled, expect reduced performance.
panic: Assertion strat == M_BESTFIT || strat == M_FIRSTFIT failed at /usr/src/sys/kern/subr_vmem.c:1050
cpuid = 0
KDB: enter: panic
[ thread pid 0 tid 0 ]
Stopped at      kdb_enter+0x3d: movl    $0,kdb_why
db> 

So I think it's fair to say that r254025 introduced the problem.

I'll go ahead and use kernel configs without DEBUG_MEMGUARD on head
until this is resolved (or I have an opportunity to test patches
for someone).

The r254025 environment is on a "spare" slice of the boot drive of
the machine, so I can leave it for now.  My more usual (active)
"head" slice is running:

FreeBSD 10.0-CURRENT #1243  r254245M/254246:1000042: Mon Aug 12 05:39:42 PDT 2013     root_at_freebeast.catwhisker.org:/common/S4/obj/usr/src/sys/GENERIC  i386

I'll be happy to test either or both.

Peace,
david
-- 
David H. Wolfskill				david_at_catwhisker.org
Taliban: Evil men with guns afraid of truth from a 14-year old girl.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.