Messages in this thread | | | Subject | Re: memory offline infinite loop after soft offline | From | David Hildenbrand <> | Date | Fri, 18 Oct 2019 13:05:10 +0200 |
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On 18.10.19 13:00, David Hildenbrand wrote: > On 18.10.19 10:55, Michal Hocko wrote: >> On Fri 18-10-19 10:38:21, David Hildenbrand wrote: >>> On 18.10.19 10:24, Michal Hocko wrote: >>>> On Fri 18-10-19 10:13:36, David Hildenbrand wrote: >>>> [...] >>>>> However, if the compound page spans multiple pageblocks >>>> >>>> Although hugetlb pages spanning pageblocks are possible this shouldn't >>>> matter in__test_page_isolated_in_pageblock because this function doesn't >>>> really operate on pageblocks as the name suggests. It is simply >>>> traversing all valid RAM ranges (see walk_system_ram_range). >>> >>> As long as the hugepages don't span memory blocks/sections, you are right. I >>> have no experience with gigantic pages in this regard. >> >> They can clearly span sections (1GB is larger than 128MB). Why do you >> think it matters actually? walk_system_ram_range walks RAM ranges and no >> allocation should span holes in RAM right? >> > > Let's explore what I was thinking. If we can agree that any compound > page is always aligned to its size , then what I tell here is not > applicable. I know it is true for gigantic pages. > > Some extreme example to clarify > > [ memory block 0 (128MB) ][ memory block 1 (128MB) ] > [ compound page (128MB) ] > > If you would offline memory block 1, and you detect PG_offline on the
s/PG_offline/PG_hwpoison/ :)
> first page of that memory block (PageHWPoison(compound_head(page))), you > would jump over the whole memory block (pfn += 1 << > compound_order(page)), leaving 64MB of the memory block unchecked. > > Again, if any compound page has the alignment restrictions (PFN of head > aligned to 1 << compound_order(page)), this is not possible. > > > If it is, however, possible, the "clean" thing would be to only jump > over the remaining part of the compound page, e.g., something like > > pfn += (1 << compound_order(page)) - (page - compound_head(page))); > > >
--
Thanks,
David / dhildenb
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