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From: David Hildenbrand <david@redhat.com>
To: Georgi Djakov <quic_c_gdjako@quicinc.com>,
	Chris Goldsworthy <quic_cgoldswo@quicinc.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>
Subject: Re: [RFC] arm64: mm: update max_pfn after memory hotplug
Date: Mon, 27 Sep 2021 19:34:02 +0200	[thread overview]
Message-ID: <1b9c4377-0a6b-b7d4-7a6b-a69f9469bb70@redhat.com> (raw)
In-Reply-To: <4f4f6e93-ddc2-c9bb-ef47-4a40f2c3d0d7@quicinc.com>

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?

I recall that we would naturally run into the limit, because

count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);

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.

-- 
Thanks,

David / dhildenb



  reply	other threads:[~2021-09-27 17:34 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-23 22:54 Chris Goldsworthy
2021-09-23 22:54 ` Chris Goldsworthy
2021-09-24  2:47   ` Florian Fainelli
2021-09-24  8:17     ` David Hildenbrand
2021-09-24 20:52       ` Chris Goldsworthy
2021-09-25  0:36       ` Sudarshan Rajagopalan
2021-09-27 15:51   ` David Hildenbrand
2021-09-27 23:22     ` Georgi Djakov
2021-09-28  6:12       ` Chris Goldsworthy
2021-09-28  7:33         ` David Hildenbrand
2021-09-27 17:22   ` Georgi Djakov
2021-09-27 17:34     ` David Hildenbrand [this message]
2021-09-27 20:00       ` Georgi Djakov
2021-09-27 20:14         ` David Hildenbrand
2021-09-27 23:01           ` Georgi Djakov
2021-09-29 10:10   ` Will Deacon
2021-09-29 10:29     ` David Hildenbrand
2021-09-29 10:42       ` Will Deacon
2021-09-29 10:49         ` David Hildenbrand
2021-09-29 11:03           ` Will Deacon
2021-09-29 12:09             ` David Hildenbrand
2021-09-29 12:51               ` Will Deacon

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