Messages in this thread | | | Subject | Re: [PATCH v1] mm: inititalize struct pages when adding a section | From | David Hildenbrand <> | Date | Fri, 27 Jul 2018 20:01:40 +0200 |
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On 27.07.2018 19:25, Pavel Tatashin wrote: > Hi David, > > On Fri, Jul 27, 2018 at 12:55 PM David Hildenbrand <david@redhat.com> wrote: >> >> Right now, struct pages are inititalized when memory is onlined, not >> when it is added (since commit d0dc12e86b31 ("mm/memory_hotplug: optimize >> memory hotplug")). >> >> remove_memory() will call arch_remove_memory(). Here, we usually access >> the struct page to get the zone of the pages. >> >> So effectively, we access stale struct pages in case we remove memory that >> was never onlined. > > Yeah, this is a bug, thank you for catching it. > >> So let's simply inititalize them earlier, when the >> memory is added. We only have to take care of updating the zone once we >> know it. We can use a dummy zone for that purpose. >> >> So effectively, all pages will already be initialized and set to >> reserved after memory was added but before it was onlined (and even the >> memblock is added). We only inititalize pages once, to not degrade >> performance. > > Yes, but we still add one more npages loop, so there will be some > performance degradation, but not severe. > > There are many conflicts with linux-next, please sync before sending > out next patch.
Indeed, although I rebased, I was working on a branch based on Linus tree ...
[...]
>> not_early: >> page = pfn_to_page(pfn); >> - __init_single_page(page, pfn, zone, nid); >> - if (context == MEMMAP_HOTPLUG) >> - SetPageReserved(page); >> + if (context == MEMMAP_HOTPLUG) { >> + /* everything but the zone was inititalized */ >> + set_page_zone(page, zone); >> + set_page_virtual(page, zone); >> + } else >> + init_single_page(page, pfn, zone, nid); >> > > Please add a new function: > memmap_init_zone_hotplug() that will handle only the zone and virtual > fields for onlined hotplug memory. > > Please remove: "enum memmap_context context" from everywhere.
All your comments make sense. Will look into the details next week and send a new version.
Thanks and enjoy your weekend!
--
Thanks,
David / dhildenb
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