Messages in this thread | | | Date | Tue, 16 Apr 2013 21:47:18 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [Bug fix PATCH v3] Reusing a resource structure allocated by bootmem |
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On Wed, 17 Apr 2013, Yasuaki Ishimatsu wrote:
> > Why not simply do what generic sparsemem support does by testing > > PageSlab(virt_to_head_page(res)) and calling kfree() if true and freeing > > back to bootmem if false? This should be like a five line patch. > > Is your explanation about free_section_usemap()? > If so, I don't think we can release resource structure like > free_section_usemap().
Right, you can't release it like free_section_usemap(), but you're free to test for PageSlab(virt_to_head_page(res)) in kernel/resource.c.
> In your explanation case, memmap can be released by put_page_bootmem() in > free_map_bootmem() since all pages of memmap is used only for memmap. > But if my understanding is correct, a page of released resource structure > contain other purpose objects allocated by bootmem. So we cannot > release resource structure like free_section_usemap(). >
I'm thinking it would be much easier to just suppress the kfree() if !PageSlab. If you can free an entire page with free_bootmem_late(), that would be great, but I'm thinking that will take more work than it's worth. It seems fine to just do free_bootmem() and leave those pages as reserved. How much memory are we talking about?
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