From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Will Deacon <will.deacon@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hanjun Guo <hanjun.guo@linaro.org>,
Yisheng Xie <xieyisheng1@huawei.com>,
Robert Richter <rrichter@cavium.com>,
James Morse <james.morse@arm.com>
Subject: Re: [PATCH 2/2] arm64: mm: enable CONFIG_HOLES_IN_ZONE for NUMA
Date: Wed, 4 Jan 2017 13:50:20 +0000 [thread overview]
Message-ID: <CAKv+Gu8MdpVDCSjfum7AMtbgR6cTP5H+67svhDSu6bkaijvvyg@mail.gmail.com> (raw)
In-Reply-To: <20170104132831.GD18193@arm.com>
On 4 January 2017 at 13:28, Will Deacon <will.deacon@arm.com> wrote:
> On Wed, Dec 14, 2016 at 09:11:47AM +0000, Ard Biesheuvel wrote:
>> The NUMA code may get confused by the presence of NOMAP regions within
>> zones, resulting in spurious BUG() checks where the node id deviates
>> from the containing zone's node id.
>>
>> Since the kernel has no business reasoning about node ids of pages it
>> does not own in the first place, enable CONFIG_HOLES_IN_ZONE to ensure
>> that such pages are disregarded.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>> arch/arm64/Kconfig | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 111742126897..0472afe64d55 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -614,6 +614,10 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK
>> def_bool y
>> depends on NUMA
>>
>> +config HOLES_IN_ZONE
>> + def_bool y
>> + depends on NUMA
>> +
>> source kernel/Kconfig.preempt
>> source kernel/Kconfig.hz
>
> I'm happy to apply this, but I'll hold off until the first patch is queued
> somewhere, since this doesn't help without the VM_BUG_ON being moved.
>
> Alternatively, I can queue both if somebody from the mm camp acks the
> first patch.
>
Actually, I am not convinced the discussion is finalized. These
patches do fix the issue, but Robert also suggested an alternative fix
which may be preferable.
http://marc.info/?l=linux-arm-kernel&m=148190753510107&w=2
I haven't responded to it yet, due to the holidays, but I'd like to
explore that solution a bit further before applying anything, if you
don't mind.
Thanks,
Ard.
next prev parent reply other threads:[~2017-01-04 13:51 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-14 9:11 [PATCH 0/2] arm64: numa: fix spurious BUG() on NOMAP regions Ard Biesheuvel
2016-12-14 9:11 ` [PATCH 1/2] mm: don't dereference struct page fields of invalid pages Ard Biesheuvel
2017-01-04 12:16 ` Will Deacon
2016-12-14 9:11 ` [PATCH 2/2] arm64: mm: enable CONFIG_HOLES_IN_ZONE for NUMA Ard Biesheuvel
2016-12-15 15:39 ` Robert Richter
2016-12-15 16:07 ` Ard Biesheuvel
2016-12-16 17:10 ` Robert Richter
2016-12-16 1:57 ` Hanjun Guo
2016-12-16 17:14 ` Robert Richter
2017-01-04 13:28 ` Will Deacon
2017-01-04 13:50 ` Ard Biesheuvel [this message]
2017-01-04 14:02 ` Will Deacon
2017-01-05 11:24 ` Robert Richter
2017-01-05 12:08 ` Will Deacon
2017-01-05 12:22 ` Robert Richter
2017-01-05 19:49 ` Robert Richter
2017-01-06 12:03 ` Will Deacon
2017-01-06 12:22 ` Ard Biesheuvel
2017-02-06 13:36 ` Robert Richter
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