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From: David Hildenbrand <>
To: Anshuman Khandual <>,,
Cc:,,, Michal Hocko <>,
	Dan Williams <>,
	Yu Zhao <>, Hsin-Yi Wang <>,
	Thomas Gleixner <>,
	Steve Capper <>,
Subject: Re: [PATCH 0/2] arm64/hotplug: Process MEM_OFFLINE and MEM_CANCEL_OFFLINE events
Date: Wed, 15 Apr 2020 09:35:33 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 15.04.20 08:39, Anshuman Khandual wrote:
> This series improves arm64 memory event notifier (hot remove) robustness by
> enabling it to detect potential problems (if any) in the future. But first
> it enumerates memory isolation failure reasons that can be sent across a
> notifier. This series does not go beyond arm64 to explore if these failure
> reason codes could be used in other existing registered memory notifiers.
> Please do let me know if there is any other potential use cases, will be
> happy to incorporate next time around. Also should we add similar failure
> reasons for online_pages() as well ?
> This series has been tested on arm64, boot tested on x86 and build tested
> on multiple other platforms.

I'm sorry, but I have to nack this series. Why?

1. A hotplug notifier should not have to bother why offlining failed. He
received a MEM_GOING_OFFLINE, followed by a MEM_CANCEL_OFFLINE. That's
all he really has to know. Undo what you've done, end of story.

2. Patch 2 just introduces dead code that should never happen unless
something is horribly broken in the core (memory offlined although
nacked from notifier). And, it (for *whatever reason*) thinks it's okay
to bail out if another notifier canceled offlining hotplugged memory.

I fail to see the benefit for core changes and

 4 files changed, 99 insertions(+), 13 deletions(-)


David / dhildenb

  parent reply	other threads:[~2020-04-15  7:35 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15  6:39 [PATCH 0/2] arm64/hotplug: Process MEM_OFFLINE and MEM_CANCEL_OFFLINE events Anshuman Khandual
2020-04-15  6:39 ` [PATCH 1/2] mm/hotplug: Enumerate memory range offlining failure reasons Anshuman Khandual
2020-04-15  6:39 ` [PATCH 2/2] arm64/hotplug: Process MEM_OFFLINE and MEM_CANCEL_OFFLINE Anshuman Khandual
2020-04-15  7:35 ` David Hildenbrand [this message]
2020-04-15 10:16   ` [PATCH 0/2] arm64/hotplug: Process MEM_OFFLINE and MEM_CANCEL_OFFLINE events Michal Hocko

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