Messages in this thread | | | Subject | Re: [PATCH v1] mm/memory_hotplug: Fix updating the node span | From | David Hildenbrand <> | Date | Wed, 30 Oct 2019 09:14:23 +0100 |
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On 27.10.19 23:27, David Hildenbrand wrote: > We recently started updating the node span based on the zone span to > avoid touching uninitialized memmaps. > > Currently, we will always detect the node span to start at 0, meaning a > node can easily span too many pages. pgdat_is_empty() will still work > correctly if all zones span no pages. We should skip over all zones without > spanned pages and properly handle the first detected zone that spans pages. > > Unfortunately, in contrast to the zone span (/proc/zoneinfo), the node span > cannot easily be inspected and tested. The node span gives no real > guarantees when an architecture supports memory hotplug, meaning it can > easily contain holes or span pages of different nodes. > > The node span is not really used after init on architectures that support > memory hotplug. E.g., we use it in mm/memory_hotplug.c:try_offline_node() > and in mm/kmemleak.c:kmemleak_scan(). These users seem to be fine. > > Fixes: 00d6c019b5bc ("mm/memory_hotplug: don't access uninitialized memmaps in shrink_pgdat_span()")
@Andrew, can we also give this a churn, we should try to get this into 5.4 due to
$ git tag --contains 00d6c019b5bc [...] v5.4-rc5
Thanks!
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Thanks,
David / dhildenb
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