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Shutemov" , Vlastimil Babka , Andrea Arcangeli , Michal Hocko , "Aneesh Kumar K . V" , Catalin Marinas , David Daney , David Miller , "H . Peter Anvin" , Hugh Dickins , Ingo Molnar , Martin Schwidefsky , Nitin Gupta , Ralf Baechle , Thomas Gleixner , Vineet Gupta , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH AUTOSEL for 3.18 086/101] asm-generic: provide generic_pmdp_establish() Thread-Topic: [PATCH AUTOSEL for 3.18 086/101] asm-generic: provide generic_pmdp_establish() Thread-Index: AQHTz5uItHHU7Tvp7UiH2lAUhDod6w== Date: Mon, 9 Apr 2018 00:41:44 +0000 Message-ID: <20180409004042.164920-36-alexander.levin@microsoft.com> References: <20180409004042.164920-1-alexander.levin@microsoft.com> In-Reply-To: <20180409004042.164920-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1062;7:FErgCJEn9YEPgZKdJrX1GXGcaFZZp9nUz9gE52B1A8Z1rOGhgacs74Pp4XvVEDq+4SWHiKvifCbqghgE8rA2ru/btZyiD2ZzLt08ntxTq3K6s4+4KEbWrrEptMWaW1R+lgvdJpJZfJ2GCy56dJSzRsLbQhB96d4XFxgpTf3cs2Z8KQ/uISYhfpoOPelJvBdYtm3y1Fr/2zkaSLuhlvhkaFS/ZcOZa5IGlLIqUcu4xKubLWHeXlZNUPVDoWvN4IIc;20:Xi/iheddKAUcOXwGggze4NfrPeViwEqf3lC+1sgnup6qP0hu906SUg1NY3qm7bNA7cJXhiCg4ep67JfWXr8TDFrbMb7IBelz/ajGi+IeRRYPva9JL5x4QS4FG75ZtivKdj9GSUiMkkC+1xQeXmpFGAeFTW1xoR6WuQJRHiP+G9A= x-ms-office365-filtering-ht: Tenant X-MS-Office365-Filtering-Correlation-Id: 24f74432-3888-4749-1cbe-08d59db2bd7a x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB1062; x-ms-traffictypediagnostic: DM5PR2101MB1062: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(28532068793085)(180628864354917)(20558992708506)(89211679590171)(190383065149520)(211936372134217)(42068640409301)(153496737603132)(104084551191319)(146099531331640); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(61425038)(6040522)(2401047)(5005006)(8121501046)(10201501046)(3231221)(944501327)(52105095)(93006095)(93001095)(3002001)(6055026)(61426038)(61427038)(6041310)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123564045)(20161123562045)(20161123558120)(20161123560045)(6072148)(201708071742011);SRVR:DM5PR2101MB1062;BCL:0;PCL:0;RULEID:;SRVR:DM5PR2101MB1062; x-forefront-prvs: 0637FCE711 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(366004)(39860400002)(376002)(39380400002)(396003)(346002)(199004)(189003)(68736007)(6512007)(316002)(486006)(6486002)(6666003)(54906003)(5660300001)(110136005)(102836004)(6306002)(14454004)(99286004)(36756003)(86612001)(72206003)(105586002)(97736004)(106356001)(2906002)(22452003)(1076002)(2900100001)(10090500001)(6436002)(3660700001)(7416002)(6116002)(575784001)(3846002)(305945005)(59450400001)(86362001)(66066001)(10290500003)(3280700002)(5250100002)(25786009)(8676002)(81166006)(8936002)(7736002)(478600001)(476003)(81156014)(26005)(4326008)(186003)(2501003)(107886003)(966005)(6506007)(2616005)(76176011)(11346002)(446003)(53936002)(22906009)(41533002)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:DM5PR2101MB1062;H:DM5PR2101MB1032.namprd21.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; x-microsoft-antispam-message-info: 200eUb/DnBJUcoJJ/dhu4hNGko+hYBBo2gaxZ8+gYs0IseBihztn98fyNFnQQmP/b2me89UaZ0htsV9FiJAH9py0QyeWk+KsbcbwU+6GNcbFs73uQjme/tVyNMOFeMZSJrkdiCPTqSX+In0QjitfkT7hjkzU8jrVHTSdQH4veuzvzTbt85zic8+R7b+7uJE+xRfnU9M0ebYYSblI9JjfhL3seevbhIrXvxR1CJgJMPPg1hP0Bdd78k4NLP2B3BjXJ7n6G2Pt8wuCXfnEYpkdhxfsYWv9rNUQ2YzNNf6H+UqExhGyUgYo1DRWiUp5CUb+vDcJR5VkNZQoHVuQBVTqRZNf73fx6Pfgt8ZCEqzBebkCaUTowbuLerrW2OiUt6yD+JhBbbJUT7a5lqrGW58LhJT6aG5hs9NHEvaaX5bMXV8= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 24f74432-3888-4749-1cbe-08d59db2bd7a X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Apr 2018 00:41:44.8616 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1062 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: "Kirill A. Shutemov" [ Upstream commit c58f0bb77ed8bf93dfdde762b01cb67eebbdfc29 ] Patch series "Do not lose dirty bit on THP pages", v4. Vlastimil noted that pmdp_invalidate() is not atomic and we can lose dirty and access bits if CPU sets them after pmdp dereference, but before set_pmd_at(). The bug can lead to data loss, but the race window is tiny and I haven't seen any reports that suggested that it happens in reality. So I don't think it worth sending it to stable. Unfortunately, there's no way to address the issue in a generic way. We need to fix all architectures that support THP one-by-one. All architectures that have THP supported have to provide atomic pmdp_invalidate() that returns previous value. If generic implementation of pmdp_invalidate() is used, architecture needs to provide atomic pmdp_estabish(). pmdp_estabish() is not used out-side generic implementation of pmdp_invalidate() so far, but I think this can change in the future. This patch (of 12): This is an implementation of pmdp_establish() that is only suitable for an architecture that doesn't have hardware dirty/accessed bits. In this case we can't race with CPU which sets these bits and non-atomic approach is fine. Link: http://lkml.kernel.org/r/20171213105756.69879-2-kirill.shutemov@linux= .intel.com Signed-off-by: Kirill A. Shutemov Cc: Vlastimil Babka Cc: Andrea Arcangeli Cc: Michal Hocko Cc: Aneesh Kumar K.V Cc: Catalin Marinas Cc: David Daney Cc: David Miller Cc: H. Peter Anvin Cc: Hugh Dickins Cc: Ingo Molnar Cc: Martin Schwidefsky Cc: Nitin Gupta Cc: Ralf Baechle Cc: Thomas Gleixner Cc: Vineet Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- include/asm-generic/pgtable.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 752e30d63904..d33fdaee5523 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -181,6 +181,21 @@ extern void pgtable_trans_huge_deposit(struct mm_struc= t *mm, pmd_t *pmdp, extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *= pmdp); #endif =20 +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +/* + * This is an implementation of pmdp_establish() that is only suitable for= an + * architecture that doesn't have hardware dirty/accessed bits. In this ca= se we + * can't race with CPU which sets these bits and non-atomic aproach is fin= e. + */ +static inline pmd_t generic_pmdp_establish(struct vm_area_struct *vma, + unsigned long address, pmd_t *pmdp, pmd_t pmd) +{ + pmd_t old_pmd =3D *pmdp; + set_pmd_at(vma->vm_mm, address, pmdp, pmd); + return old_pmd; +} +#endif + #ifndef __HAVE_ARCH_PMDP_INVALIDATE extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long addr= ess, pmd_t *pmdp); --=20 2.15.1