Re: [PATCH] [BUGFIX] mm: hugepages can cause negative commitlimit
From: Andrew Morton
Date: Fri May 20 2011 - 16:04:19 EST
On Thu, 19 May 2011 17:11:01 -0500
Russ Anderson <rja@xxxxxxx> wrote:
> OK, I see your point. The root problem is hugepages allocated at boot are
> subtracted from totalram_pages but hugepages allocated at run time are not.
> Correct me if I've mistate it or are other conditions.
>
> By "allocated at run time" I mean "echo 1 > /proc/sys/vm/nr_hugepages".
> That allocation will not change totalram_pages but will change
> hugetlb_total_pages().
>
> How best to fix this inconsistency? Should totalram_pages include or exclude
> hugepages? What are the implications?
The problem is that hugetlb_total_pages() is trying to account for two
different things, while totalram_pages accounts for only one of those
things, yes?
One fix would be to stop accounting for huge pages in totalram_pages
altogether. That might break other things so careful checking would be
needed.
Or we stop accounting for the boot-time allocated huge pages in
hugetlb_total_pages(). Split the two things apart altogether and
account for boot-time allocated and runtime-allocated pages separately. This
souds saner to me - it reflects what's actually happening in the kernel.
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