Messages in this thread | | | Subject | Re: [PATCH v2 1/3] mm/shuffle: don't move pages between zones and don't read garbage memmaps | From | David Hildenbrand <> | Date | Tue, 23 Jun 2020 09:39:19 +0200 |
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> Hmm.. I thought this is the behavior for early section, while it looks current > code doesn't work like this: > > if (section_is_early && memmap) > free_map_bootmem(memmap); > else > depopulate_section_memmap(pfn, nr_pages, altmap); > > section_is_early is always "true" for early section, while memmap is not-NULL > only when sub-section map is empty. > > If my understanding is correct, when we remove a sub-section in early section, > the code would call depopulate_section_memmap(), which in turn free related > memmap. By removing the memmap, the return value from pfn_to_online_page() is > not a valid one.
I think you're right, and pfn_valid() would also return true, as it is an early section. This looks broken.
> > Maybe we want to write the code like this: > > if (section_is_early) > if (memmap) > free_map_bootmem(memmap); > else > depopulate_section_memmap(pfn, nr_pages, altmap); >
I guess that should be the way to go
@Dan, I think what Wei proposes here is correct, right? Or how does it work in the VMEMMAP case with early sections?
-- Thanks,
David / dhildenb
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