Re: Public repro case! Re: [PATCH/RFC] Allow writing loose objects that are corrupted in a pack file

[Linus Torvalds <torvalds@linux-foundation.org>]

On Wed, 7 Jan 2009, R. Tyler Ballance wrote:
>
> My most esteemed colleague (Ken aka kb) who pointed out the memory issue
> was on the right path (I think), and I have a reproduction case you can
> try with your very own Linux kernel tree!
> 
> WOO!
> 
> I set ulimit -v really low (150M), and the operations I made got an
> mmap(2) fatal error, but there is a sweet spot that I found, see the
> transcript below.

This is indeed the packfile mapping. The sweet spot you found depends on 
how big the biggest two pack-files are, I do believe.

And if you do that

	[core]
		packedgitwindowsize = 64M

I think you'll find that it works. Of course, with a _really_ low ulimit, 
you'd need to make it even smaller, but at some point you start hitting 
other problems than the pack-file limits, ie just the simple fact that git 
wants and expects you to have a certain amount of memory available ;)

Can you cnfirm that your "reproducible" case starts working with that 
addition to your ~/.gitconfig? If so, the solution is pretty simple: we 
should just lower the default pack windowsize.

		Linus