Re: [PATCH 2.6.18-rc4 00/10] Kernel memory leak detector 0.9

From: Michal Piotrowski
Date: Thu Aug 17 2006 - 10:42:56 EST

Hi Catalin,

On 17/08/06, Catalin Marinas <catalin.marinas@xxxxxxxxx> wrote:
On 13/08/06, Michal Piotrowski <michal.k.k.piotrowski@xxxxxxxxx> wrote:
> It's kmemleak 0.9 issue. I have tested kmemleak 0.8 on 2.6.18-rc1and
> 2.6.18-rc2. I haven't seen this before.

it looks like it was caused by commit
fc818301a8a39fedd7f0a71f878f29130c72193d where free_block() now calls
slab_destroy() with l3->list_lock held.

I'll revert this commit.

The prio_tree use (which doesn't alloc memory) instead of the
radix_tree is about 4 times slower when scanning the memory and I
don't think I'll use it.

It leaves me with the options of either implementing my own memory
allocator based on pages (including a simple hash table instead of
radix tree) or fix the locking in kmemleak so that memory allocations
happen without memleak_lock held. The latter is a bit complicated as
well since any slab allocation causes a re-entrance into kmemleak.

Any other suggestions?

Please talk with Christoph Lameter, he is working on Modular Slab.
Maybe he can help with this problem.




Michal K. K. Piotrowski
LTG - Linux Testers Group
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