Messages in this thread | | | Date | Mon, 27 Sep 2021 23:00:25 +0300 | Subject | Re: [RFC] arm64: mm: update max_pfn after memory hotplug | From | Georgi Djakov <> |
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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.
Thanks, Georgi
> wouldn't really do what you would expect either. But you could > force-read beyond max_pfn, yes, because the count computation was just > weird. > > > I think the real issue is not properly adjusting max_pfn in the first > place when we introduced memoruy hotplug on arm64
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