Re: [PATCH 1/2] arm64: avoid alloc memory on offline node

From: Punit Agrawal <punit.agrawal@arm.com>
To: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	tnowicki@caviumnetworks.com, Xie XiuQi <xiexiuqi@huawei.com>,
	linux-pci@vger.kernel.org,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Will Deacon <will.deacon@arm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	linux-mm@kvack.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Bjorn Helgaas <helgaas@kernel.org>,
	linux-arm <linux-arm-kernel@lists.infradead.org>,
	Hanjun Guo <guohanjun@huawei.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	zhongjiang <zhongjiang@huawei.com>,
	wanghuiqiang@huawei.com
Subject: Re: [PATCH 1/2] arm64: avoid alloc memory on offline node
Date: Tue, 26 Jun 2018 18:27:01 +0100	[thread overview]
Message-ID: <87muvhwja2.fsf@e105922-lin.cambridge.arm.com> (raw)
In-Reply-To: <20180622184223.00007bc3@huawei.com> (Jonathan Cameron's message of "Fri, 22 Jun 2018 18:42:23 +0100")

Jonathan Cameron <jonathan.cameron@huawei.com> writes:

[...]

>
> I'll test it when back in the office, but I had a similar issue with
> memory only nodes when I moved the SRAT listing for cpus from the 4
> 4th mode to the 3rd node to fake some memory I could hot unplug.
> This gave a memory only node for the last node on the system.
>
> When I instead moved cpus from the 3rd node to the 4th (so the node
> with only memory was now in the middle, everything worked).
>
> Was odd, and I'd been meaning to chase it down but hadn't gotten to it
> yet.  If I get time I'll put together some test firmwares as see if there
> are any other nasty corner cases we aren't handling.

If you get a chance, it'd be really helpful to test reversing the
ordering of entries in the SRAT and booting with a restricted
NR_CPUS.

This issue was found through code inspection.

Please make sure to use the updated patch from Lorenzo for your
tests[0].

[0] https://marc.info/?l=linux-acpi&m=152998665713983&w=2

>
> Jonathan
>
>> 
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