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Reply-To: Gavin Shan <gshan@redhat.com>
Subject: Re: [PATCH] arm64/mm: Reject invalid NUMA option
To:     Will Deacon <will@kernel.org>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Mark Rutland <mark.rutland@arm.com>, catalin.marinas@arm.com,
        linux-kernel@vger.kernel.org, shan.gavin@gmail.com,
        linux-arm-kernel@lists.infradead.org
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From:   Gavin Shan <gshan@redhat.com>
Message-ID: <858cb997-d187-e605-446e-24ac4169b147@redhat.com>
Date:   Tue, 28 Apr 2020 18:56:02 +1000
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Hi Will,

On 4/28/20 5:25 PM, Will Deacon wrote:
> On Tue, Apr 28, 2020 at 02:35:20PM +1000, Gavin Shan wrote:
>> On 4/28/20 1:09 PM, Steven Rostedt wrote:
>>
>> [...]
>>
>>>
>>> Could this be a bug in the implementation of strncmp() in
>>> arch/arm64/lib/strncmp.S. As I don't know arm64 assembly, I have no i=
dea
>>> what it is trying to do.
>>>
>>> But strncmp("o","off",3) returning zero *is* a bug.
>>>
>>
>> I think it's false alarm. The patch has been in my local repo for a wh=
ile.
>> I checked out 5.7.rc3 and tried passing "numa=3Do" to the kernel, @num=
a_off
>> is unchanged and its value is false. I also check the return value fro=
m
>> strncmp() as below, it's correct. Nothing is broken. I should have ret=
ested
>> before posting it. Sorry for the noise. Please ignore the crap patch :=
)
>=20
> Hmm, it's still worrying that you had that patch kicking around though,=
 as
> it sounds like it /used/ to be broken. Would you be able to test the LT=
S
> kernels (5.4, 4.19, 4.14, 4.9, 4.4) to check that we're not missing a
> backport, please? Sorry to be a pain, but I'd like to get to the bottom=
 of
> this!
>=20

Sure, There are nothing to worry. I tried the following branches of the s=
table
tree. They all looks good in this regard.

    linux-5.6.y
    linux-5.5.y
    linux-5.4.y
    linux-5.3.y
    linux-4.19.y
    linux-4.9.y

linux-4.4.y isn't tried because the corresponding parameter starts to exi=
st
from linux-4.7.y: 1a2db300348b ("arm64, numa: Add NUMA support for arm64 =
platforms.")

    # git tag --contains 1a2db300348b | sort -V | head -n 3
    v4.7
    v4.7-rc1
    v4.7-rc2

In the experiment, the following pr_info() is added and I got same output
from above branches:

diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index b1e42bad69ac..1e0e3491de54 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -44,6 +44,8 @@ static __init int numa_parse_early_param(char *opt)
         if (!strncmp(opt, "off", 3))
                 numa_off =3D true;
 =20
+       pr_info("=3D=3D=3D> numa_off=3D%s\n", numa_off ? "true" : "false"=
);
+


[    0.000000] NUMA: =3D=3D=3D> numa_off=3Dfalse


There is unrelated compiling warnings in linux-5.3.y:

drivers/pinctrl/pinctrl-rockchip.c: In function =91rockchip_gpio_set_conf=
ig=92:
drivers/pinctrl/pinctrl-rockchip.c:2783:3: warning: this statement may fa=
ll through [-Wimplicit-fallthrough=3D]
    rockchip_gpio_set_debounce(gc, offset, true);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/pinctrl/pinctrl-rockchip.c:2795:2: note: here
   default:
   ^~~~~~~


> Thanks,
>=20
> Will
>=20

Thanks,
Gavin