Received-SPF: pass (google.com: domain of linux-kernel+bounces-204446-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
From: Zi Yan <ziy@nvidia.com>
To: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
Cc: Shuah Khan <shuah@kernel.org>, Andrew Morton <akpm@linux-foundation.org>,
 willy@infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
 gost.dev@samsung.com, mcgrof@kernel.org, linux-kselftest@vger.kernel.org,
 Pankaj Raghav <p.raghav@samsung.com>
Subject: Re: [PATCH] selftests/mm: use volatile keyword to not optimize mmap
 read variable
Date: Thu, 06 Jun 2024 07:21:27 -0700
Message-ID: <4DEF0691-B0F7-4A9B-A8F4-115304419B0C@nvidia.com>
In-Reply-To: <20240606135835.600022-1-kernel@pankajraghav.com>
References: <20240606135835.600022-1-kernel@pankajraghav.com>
Content-Type: multipart/signed;
 boundary="=_MailMate_388E47E6-D338-4A30-96DA-6174F3F35436_=";
 micalg=pgp-sha512; protocol="application/pgp-signature"
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?us-ascii?Q?us7gVA3yZTMqtAPbCkV5lprdCLTYUPi+AfII+LIqVNxK3h9dmVLpijxgjfdm?=
 =?us-ascii?Q?X9T79H1fAUyyCYxx8EpIA7itqxre/qe4SlGcRO+tpwtqHSE4qVHcAptcapEU?=
 =?us-ascii?Q?OHOFHtVgQmVbCH8VI+AJdZNg6BFzFQmSIxSizpqimj8/K923Yt11rxXrKHDq?=
 =?us-ascii?Q?P1Rx+UpGVxCE+AvwhlAvx2UvCg0JVqRQJA9qSuIKSsP3WgLgb3JQsgqpeZ+l?=
 =?us-ascii?Q?jB0v0emuMEy20GlYFc7G719W2q7FpfZX5xMRUcePlEkW0So/nPTlYiVHogio?=
 =?us-ascii?Q?QRTF8SfUe5sBSnpkI/g3sH3jZar8fbcUWQ8bos1EnpgizX+cfg3EoDE22kRZ?=
 =?us-ascii?Q?SEcQ0Hrxc+vP66dNZ+VPvmTq/iTS4SjkTabmjTjNqqOD9THhWCf8uFYNou5w?=
 =?us-ascii?Q?GlI8KUDBThCnbR2jkfeXDtjoI8dK+HnvjMAh6oEcO+k6JQD1LJzp3/m7NEs7?=
 =?us-ascii?Q?6jqOhGTonHfQiUmFPLYMtDOHYpg6MBrIyOO9rDJKM10u5dzIUaMqZt/+dcAs?=
 =?us-ascii?Q?uvFQFRE8L6sCEful7h4zPL5IALcWqeQEsgxedUU+ens22GNisbDnvTOIQMC4?=
 =?us-ascii?Q?t617kN75XEcydqq06VQFDW5Vvc7HYM2SfG1R0CQuN9Fy/3XVtpWryjHH5Jio?=
 =?us-ascii?Q?1Wjbozd1T9fbPvbFY5l2Y+vE016nHEO+F+VZ0S9HhXY9O5vK/ndJhWbJ3hjt?=
 =?us-ascii?Q?pICA4ETFAQ4vyzQuJ6R4OV4XPFNarEXY8yYRHnXaZD2L0teAyG1p6te6imLS?=
 =?us-ascii?Q?pJ4DOjnGd+jBHDZ+IwnAKNN357oTOqFaX0M1BhWHA0a+UayyFVlRI0/MFoVU?=
 =?us-ascii?Q?Bo5TPVWmdmNxE+lCsYA7cLhXWjMyyT4vlhDDhnDsVxXmTcF4DQdaQ4QGMnec?=
 =?us-ascii?Q?iWaplubSbpc2Xiqp5qXqHB68mT3GancH8JZvwSf765tIpioYGi3p5RWxLV/R?=
 =?us-ascii?Q?HOOIooVuNFp/eD9vhGYKnqKKNHE+NDMhZV+fFXvicgYFoE/HhsXVoq1jtW8p?=
 =?us-ascii?Q?FYO74pI0uRIat9c2Wib1/SXTW5h60dUWGkIrOHur666YppBitQOrSEhvIGFj?=
 =?us-ascii?Q?9L3Xwi7hd96C+pVu5XPzGIWgRFxOVsvqIpLNeKp35fhLTcTL1nELEDwfzuRi?=
 =?us-ascii?Q?YGG4SCHf6ndgoQx+ka1UDjAkSEw4D4waXR0PbfJFLOy4WfrJPKA89fSO/ANB?=
 =?us-ascii?Q?Vv0xH/QRKZbCCjqEq/zb6NsqwjajkbUsNUvILUXf6er39mE8v0n8MBj7823I?=
 =?us-ascii?Q?ugnCpXYMdh3j0oGFyYE8bIkOiPxIJiDP+L0t55ecY98Qh4ziRUHADRJQS8Jl?=
 =?us-ascii?Q?OZZMKtfUtyLthX0wGbVHsw1PDcqrg6iOydagAZtzlmL4sJJzK7oWVYyA7j+c?=
 =?us-ascii?Q?MhVCVIWDVlHFtuuw4DWwTLxEYRRjCkJED/AUKZL+hJ5XapYTydeFDD9Ux0Oa?=
 =?us-ascii?Q?Lh+HIWke8VZkmZbe8A6NnupCSxYXmkllMSNq5sGfeL31P/t838JKaNzAY3cg?=
 =?us-ascii?Q?7PG8dQffm3NcM/Kb0wTwiTArjT9TJv9PUSlSG/yO9jaCaKcoA8aEHo5sHfSQ?=
 =?us-ascii?Q?pkt8uFEG+kAgpq8TN6I=3D?=
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: f3c378c9-ed9d-48ae-17b6-08dc8633f655
X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB5744.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Jun 2024 14:21:31.5576
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: pL4YjAgOGSoBm6SRulhaGWH1kJ22xF5qt27s2gJevZ8Xcio4OehUvJ9KhgBtBjpA
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7886

--=_MailMate_388E47E6-D338-4A30-96DA-6174F3F35436_=
Content-Type: text/plain

On 6 Jun 2024, at 6:58, Pankaj Raghav (Samsung) wrote:

> From: Pankaj Raghav <p.raghav@samsung.com>
>
> create_pagecache_thp_and_fd() in split_huge_page_test.c used the
> variable dummy to perform mmap read.
>
> However, this test was skipped even on XFS which has large folio
> support. The issue was compiler (gcc 13.2.0) was optimizing out the
> dummy variable, therefore, not creating huge page in the page cache.
>
> Add volatile keyword to force compiler not to optimize out the loop
> where we read from the mmaped addr.
>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
>  tools/testing/selftests/mm/split_huge_page_test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Acked-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

--=_MailMate_388E47E6-D338-4A30-96DA-6174F3F35436_=
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename=signature.asc
Content-Type: application/pgp-signature; name=signature.asc

-----BEGIN PGP SIGNATURE-----

iQJDBAEBCgAtFiEEh7yFAW3gwjwQ4C9anbJR82th+ooFAmZhxegPHHppeUBudmlk
aWEuY29tAAoJEJ2yUfNrYfqKVWQQAJu3Xas417qiFgI9qxQNwlVQxhcPoTlehgdo
xh4QwoJVQxHCid5fSneDTrroL8CEgYAcgROh5mItEJnLzkDWovD+mOydR7RNW5ts
w7hl9MTPItip94pmKcplh6WnxF8tsbWlkXZQQyEceiNSQ7JVC/2XSt8MXhaxMJ5h
kSiVshYl4/+oOHF5FuZTDEGlIyg/cAQkY7YH9CF56gYkIVFrnQtyZA3y+MQ4tRkI
MloeftwpXa5y8kUrzy5Al5YNVBMN/7JTlvbYQIxpOeYNuLhA54vaVTMJiH7V1zLr
rwkY4tsUmVU3a6dLa+ekiLn5SKu7l+tksKLooeiDiT95wcJaZh7k1k8sLkxk63Ce
kJ5xrdHts+ohezeYooVseR0DZ96m5GQmCXSKCWFoJ7PMoHGdUjv91jyl4jeEM0Qu
f8XYXArH8s+MtLBWX/3HH7HUv22yFL694HCVMfLWf/WmWqfxE6pQot5NQVNZqSNy
BHlZOIazyvMnRILCypXukgTje4jar93NIjvvI9MVCz3QaodMtOlvIX0RUpO2P8aS
xXlsz6nM+fDKVPU/seNjjwTXh08QnpJoMY4Qa7uqiJ7X+kEBJ6K3y6n2jIHvGyDg
62DG4LLOrc7E7DfvK0B/Tppo/SbSPg5mt+wTEb1Havxfe+aehS3f7oACx8wBjXeK
S3ynFX3g
=e6x1
-----END PGP SIGNATURE-----

--=_MailMate_388E47E6-D338-4A30-96DA-6174F3F35436_=--