On Mon, 29 Apr 2002, John Baldwin wrote:

> 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. 

That was what I was theorizing when I made the change, but I haven't
really had much time lately to read the UMA code, so it's greek to me. :-)

Robert N M Watson             FreeBSD Core Team, TrustedBSD Project
[EMAIL PROTECTED]      NAI Labs, Safeport Network Services

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