Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   "Zhang, Qiang1" <qiang1.zhang@intel.com>
To:     Andrew Morton <akpm@linux-foundation.org>
CC:     "ryabinin.a.a@gmail.com" <ryabinin.a.a@gmail.com>,
        "dvyukov@google.com" <dvyukov@google.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Alexander Potapenko" <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        kasan-dev <kasan-dev@googlegroups.com>
Subject: RE: [PATCH] kasan: Prevent cpu_quarantine corruption when CPU offline
 and cache shrink occur at same time
Thread-Topic: [PATCH] kasan: Prevent cpu_quarantine corruption when CPU
 offline and cache shrink occur at same time
Thread-Index: AQHYT6ulsqnvKUJhXEyVsracxSIbz6z6+R4AgAXGCXA=
Date:   Mon, 25 Apr 2022 14:25:16 +0000
Message-ID: <PH0PR11MB5880B595E4836DF66928692DDAF89@PH0PR11MB5880.namprd11.prod.outlook.com>
References: <20220414025925.2423818-1-qiang1.zhang@intel.com>
 <20220421150746.627e0f62363485d65c857010@linux-foundation.org>
In-Reply-To: <20220421150746.627e0f62363485d65c857010@linux-foundation.org>
Accept-Language: en-US
Content-Language: en-US
dlp-product: dlpe-windows
dlp-version: 11.6.401.20
dlp-reaction: no-action
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?ffFJe2GNdeQ3POxQELmOI4ekTeRWmDAunhmsH5XnvptRX4YC9/ECEXHLZh9Q?=
 =?us-ascii?Q?hg1wUX18LytpE1Te2g+bD8c/iA40VgH6fcDOEOeV4QWn5OhcNzaT5zAAOiNC?=
 =?us-ascii?Q?WWR6yRe+1PT8m/TGOj65i6uRQucEs3Ddohl3/HDWLs1AToCXgWGOzCSJCSHo?=
 =?us-ascii?Q?1lIAw3PgfhY2YcaBc35p5/aCM3/JCsMDVRiaok0UTi650EfR3aX++QhzLKHL?=
 =?us-ascii?Q?dP7LpB4J6ZhvLuigkBlEud4L+T3TOp44fLpIalRrTFuoBrL9gd7Hx161IWaw?=
 =?us-ascii?Q?EDMoGYaimcs4PwIGOUKIReuD9Wm0VVrgqWDSx5hGRQNHt6TQ+wZacetbVuU/?=
 =?us-ascii?Q?3x76nuIf5KMGQUou87J5NmdzROVInB1Gg0KBIGjhI53b8Wlzgi6MHG/s5f8J?=
 =?us-ascii?Q?2e14BYxcss0hOgnwi2TUA7qoNqo5J/iN8ZlXOyLwtn5iFUDDcWbS790i80vu?=
 =?us-ascii?Q?YMDedCu3rqz5Q3raDb/eLsziYiLUFVsU2oVMHSCvBxn9frzlUoRHU2sKczPO?=
 =?us-ascii?Q?TDQUCNUgr6jld/KUt5j0FnAYFPWto0slMeBX8doHQKHKj4kd3I5LYF10TM5d?=
 =?us-ascii?Q?PXl/Na980itVRHpSNKZFFz3qShyX7v+B4O+d+Ob6YL41CnlmC0018QEoclFA?=
 =?us-ascii?Q?XMJwi+T6A9ZQ1RexgTdQlUeq92BDroNLGVQmKlpyZ9hHhJhhs+OUKXD86hrt?=
 =?us-ascii?Q?1jjdX/mmFDbYTPxN/0ihQjbhMV32ZzOJRBsgeJT0ynN6A4iQGITA/DLeb/hE?=
 =?us-ascii?Q?jbT711s7gwW74V2cFqUOL5+pQH4AlGuY7TRYR+kQ0SxJERsmYzwE9aK/bU7R?=
 =?us-ascii?Q?TH8TbThn4kdaELrNaDpogEGJb62dI1qUYeTofPwA0CJjchLw5F4Yx93ppWn/?=
 =?us-ascii?Q?sWkGLFDSOCwtTp9ZnJOeyaFmhTC8FKyKBW73M6ZFF8TSoSKCFI3Z5qLv7bVZ?=
 =?us-ascii?Q?AmwDrBVD8sly06KXrP4JoYlOhLg99LKksiQl9NrGunWtD7s8uymbN1Syn/Ym?=
 =?us-ascii?Q?UIzJ/T/c37fkI4/XlYicDYKtJWce6YEugyCP3SZvPQ5gmBNyWmI2veefc/YI?=
 =?us-ascii?Q?zdj3MA17AsV3yJitUsUuswhQyOwBKWRXTutMqhcqUMNZ1KPaq8cAHp6TvJCH?=
 =?us-ascii?Q?mN9sXAKkwLAkXaBdk6COm4KDGOi3QBInwdkN4aUleHlrxmwZGxjNp/UPuJai?=
 =?us-ascii?Q?iR30/mF5Jl91L0RI8TDf7iuKRh/YlH0miztStD1AlbY4dOUKvp1ooroa1D/r?=
 =?us-ascii?Q?LVFGIkPAqRTJLt26BJTdD3EnC1yghCzVf3IPIgaSyfXBrVLhqPqJz1dKqcsY?=
 =?us-ascii?Q?XdHniIwCeBPDctTPZv7UTFNUGSPfD0LNPDg0DiP/jHimXivTA26ndRNpGCJL?=
 =?us-ascii?Q?4TZdgm7n+zepIqcmW+NYRNDlCirIbCLllSxTUBt9c9Vl1kUszK8qi7AMr4L5?=
 =?us-ascii?Q?SuBcHJ4AJs1JvizIqO1XeJPFi6euSLib6jyVr7JV8r4ryv7WA/fTLSCOoiE+?=
 =?us-ascii?Q?5DIyGBQYU5CMPtCeQFaMT3CvSBAw793Sebu20WY7j60NKjN1jLjY5YNk9cLL?=
 =?us-ascii?Q?ByNrCep/oi2BOmUtld6T7Cv53nu4QJ6QfOxGh5Zvs4ATGaIGX488csYeUZYO?=
 =?us-ascii?Q?s1PqOwtb0UbIiJcug4sbaPScIohB+W1tobqzRFnxo4Bos/n4WD8NIaqGEyAx?=
 =?us-ascii?Q?USoSA2ftPQlttwAU0aul2pQW0HNmJ4UuaZetovmcMvK61W518iD5ciapXsoi?=
 =?us-ascii?Q?PXEP5wu3fQ=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: PH0PR11MB5880.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: a98c373f-efdf-467b-c96b-08da26c76b13
X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Apr 2022 14:25:16.2840
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: ADg5MSbUpCZhxyPP8MKtfHVbjPfGz9690kcm/gPDL52zHeJQBvBPPxoXhLGCukTqJ4MArIII+3fEyRzgfvRVKw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR11MB4973
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-3.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, 14 Apr 2022 10:59:25 +0800 Zqiang <qiang1.zhang@intel.com> wrote:

> The kasan_quarantine_remove_cache() is called in kmem_cache_shrink()/=20
> destroy(), the kasan_quarantine_remove_cache() call is protected by=20
> cpuslock in kmem_cache_destroy(), can ensure serialization with=20
> kasan_cpu_offline(). however the kasan_quarantine_remove_cache() call=20
> is not protected by cpuslock in kmem_cache_shrink(), when CPU going=20
> offline and cache shrink occur at same time, the cpu_quarantine may be=20
> corrupted by interrupt(per_cpu_remove_cache operation). so add=20
> cpu_quarantine offline flags check in per_cpu_remove_cache().
>=20
> ...
>

>Could we please have some reviewer input here?

> --- a/mm/kasan/quarantine.c
> +++ b/mm/kasan/quarantine.c
> @@ -330,6 +330,8 @@ static void per_cpu_remove_cache(void *arg)
>  	struct cpu_shrink_qlist *sq;
>  #endif
>  	q =3D this_cpu_ptr(&cpu_quarantine);
> +	if (READ_ONCE(q->offline))
> +		return;
>  #ifndef CONFIG_PREEMPT_RT
>  	qlist_move_cache(q, &to_free, cache);
>  	qlist_free_all(&to_free, cache);

>It might be helpful to have a little comment which explains why we're doin=
g this?

Sorry for late reply,  may be add some comment:

Ensure the ordering between the writing to q->offline and per_cpu_remove_ca=
che.
prevent cpu_quarantine be corrupted by interrupt.

Is this OK ?

Thanks
Zqiang