Messages in this thread | | | Subject | Re: [RFC] arm64: mm: update max_pfn after memory hotplug | From | David Hildenbrand <> | Date | Mon, 27 Sep 2021 22:14:24 +0200 |
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On 27.09.21 22:00, Georgi Djakov wrote: > On 9/27/2021 8:34 PM, David Hildenbrand wrote: >> On 27.09.21 19:22, Georgi Djakov wrote: >>> On 9/24/2021 1:54 AM, Chris Goldsworthy wrote: >>>> From: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com> >>>> >>>> After new memory blocks have been hotplugged, max_pfn and max_low_pfn >>>> needs updating to reflect on new PFNs being hot added to system. >>>> >>>> Signed-off-by: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com> >>>> Signed-off-by: Chris Goldsworthy <quic_cgoldswo@quicinc.com> >>> >>> Thanks for the patch, Chris! >>> >>> With this patch, the data in /proc/kpageflags appears to be correct and >>> memory tools like procrank work again on arm64 platforms. >>> >>> Tested-by: Georgi Djakov <quic_c_gdjako@quicinc.com> >>> >>> Maybe we should add fixes tag, as it has been broken since the following >>> commit: >>> Fixes: abec749facff ("fs/proc/page.c: allow inspection of last section >>> and fix end detection") >> >> Are you sure that that commit broke it? > > Reverting the above commit also "fixes" kpageflags, otherwise > kpageflags_read() returns 0 in the following check: > if (src >= max_dump_pfn * KPMSIZE) > return 0; > >> I recall that we would naturally run into the limit, because >> >> count = min_t(size_t, count, (max_pfn * KPMSIZE) - src); > > The function returns before we reach this line.
That is the old code. I don't see how the behavior of the old code with wrong max_pfn was doing what it's supposed to do.
page_idle and page_owner also rely on max_pfn. The root issue is that max_pfn wasn't updated properly.
-- Thanks,
David / dhildenb
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