Re: More problems in setup_pcpu_remap()
From: Tejun Heo
Date: Thu Apr 02 2009 - 00:43:20 EST
Hello,
David Miller wrote:
> The way this code is currently designed, it can exhaust all of the
> VMALLOC address space on both x86 and x86_64, and then some.
>
> It allocates PMD_SIZE * num_possible_cpus() of vmalloc space.
>
> PMD_SIZE is 2MB, num_possible_cpus() can be up to 4096....
> which can easily exceed (VMALLOC_END - VMALLOC_START)
>
> Initially I had set out to implement sparc64 support for the new
> per-cpu stuff, but it looks like I'm stuck finding bugs in the x86
> implementation instead :-)
Eh... sorry about that. :-)
I guess we'll have to put a cap on how high possible cpus can be for
remap allocator. e.g. if single chunk size is over 20% of the whole
vmalloc area, don't use remap. Does anyone have a good random %
number on mind?
Thanks.
--
tejun
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