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Date:      Mon, 29 Apr 2002 08:56:51 -0400 (EDT)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Robert Watson <rwatson@FreeBSD.org>
Cc:        jeff@FreeBSD.org, current@FreeBSD.org
Subject:   Re: page fault in _mtx_lock_flags
Message-ID:  <XFMail.20020429085651.jhb@FreeBSD.org>
In-Reply-To: <Pine.NEB.3.96L.1020428235948.64976V-200000@fledge.watson.org>

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On 29-Apr-2002 Robert Watson wrote:
> 
> If I apply the attached diff to the kern_malloc.c, backing out a portion
> of kern_malloc.c:1.99, the rate of panics plummets.  Previously, I could
> have a box panic within five minutes of getting the crash boxes spinning. 
> Now I've been going for about 40 minutes without any perceived failures
> (i.e., no panics).  I have no idea why this fixes the problem, but David
> Wolfskill pointed me at that particular revision as being a source of
> related problems for him.  I'm going to leave the boxes running overnight
> and see what I bump into.  It would be nice to know if this is masking the
> problem, or fixing the problem, and if so, why. 

You have memory corruption it looks like.  I think the patch adds new buckets
of larger sizes.  Perhaps the problem is a bug in uma where someone allocates
something bigger than the largest bucket, and the chunk they get back is only
the size of an item in the largest bucket, thus when the code writes to the
end of the structure it is overwriting other memory.

-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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