On 23.06.20 09:39, David Hildenbrand wrote: >> 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? >
Especially, if you would re-hot-add, section_activate() would assume there is a memmap, it must not be removed. @Wei, can you send a patch? -- Thanks, David / dhildenb
