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Sun, 2 Sep 2018 13:04:12 +0000 Received: from CY4PR21MB0776.namprd21.prod.outlook.com ([fe80::7c3a:eea8:1391:1611]) by CY4PR21MB0776.namprd21.prod.outlook.com ([fe80::7c3a:eea8:1391:1611%7]) with mapi id 15.20.1143.000; Sun, 2 Sep 2018 13:04:12 +0000 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Stefan Hajnoczi , Dave Jiang , Sasha Levin Subject: [PATCH AUTOSEL 4.18 045/131] device-dax: avoid hang on error before devm_memremap_pages() Thread-Topic: [PATCH AUTOSEL 4.18 045/131] device-dax: avoid hang on error before devm_memremap_pages() Thread-Index: AQHUQr1obE7dzdp+1UGq0dqcZSilNQ== Date: Sun, 2 Sep 2018 13:03:57 +0000 Message-ID: <20180902064601.183036-45-alexander.levin@microsoft.com> References: <20180902064601.183036-1-alexander.levin@microsoft.com> In-Reply-To: <20180902064601.183036-1-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;CY4PR21MB0135;6:XzMnN1u3bxjR6O1nsotMfTnuLPLVsvg4r6fDriWIFmStJhhpXTkSivcMxnJC04fbIdfT/KuNEIM/7eDifNhrvqEu3Rjhc5pJ3fYjAnhbu2/hJPafNvNJ1ZVkqfb6QCNEC8bmjT+dNa3vohLDgZ3DSbVamxYxDJ+86rsYwqLO1vXhgu8LTx0oLi81laNlfPSBj0OvPbB/XK+1QZiVHQo2EK3BruLwHKDRZakTXrT4aWZGz0u1fON49kBJfAOCG7thM5sFm7L9nDcWzPGLE0GO/xyqC+vRrJxnrQ5ErNoqzhEqzEz0rWBG8kVZHd8th4CZa/9QXNQTSECSoMNeC/gqBdOwVn3bPMEy80mlvbN9xa0wAnn6H98zrw9r/r78KDIZ+BCKq14+A2O1Y6JgHA/PDE7E/nQVPdKdyyzjGvuo+0LEGRVTgZn9ktPmpIcxIHCmp27QHScJoVu/jE144MjI6g==;5:mLTA36VgutLlh/TdOPin1w1wUYCprSqA4c+2mQf5r3lVMArOHtrc1POoxb7On2GUMbf1AYFjH5ve1rAs3ag1fiua4HrgIh0J1MwOjGpOIkc14tIA4uKISQsil2qdk7iTvzX+PGaLdvJNxkMQprChJZw+OdtDKEZlLfie7cOJn9A=;7:7iSPzd6J2p1roJh6dSln0/+aP9Fmx+TSECBtYdz0q83YUPjHKmVCijCKcymEk28TDF9bM+46+72PJjFX4KWxHGTEZoe19EEPGB+1INN58ckG2pVuHw8tAv7z/WW3ALqmk88ZZvD/5/QdK+QzZN0o32tnPETxm6EgtxUCDrLC17Fhl9NDM15jwpE6xZN2R0yBY8TUrzXCCpBa4mycwtx2MLz0LicsIhXXRLgyY/ZLqCjEAIlRg20Sj4KasORg7Djp x-ms-office365-filtering-correlation-id: c2965d39-3126-40ff-27e2-08d610d4942b x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0;PCL:0;RULEID:(7020095)(4652040)(4534165)(4627221)(201703031133081)(201702281549075)(5600074)(711020)(4618075)(2017052603328)(7193020);SRVR:CY4PR21MB0135; 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received-spf: None (protection.outlook.com: microsoft.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: vzcD4Knj1kHyYocKmzW+vCoJWRXwCom/6eiDEPuZ0S/adA92F4lIm7YOO3th3jSnuacfIsD8XXYXQ8AYJqyb3nZYxXsjRkB91Csr5d+xB0tYSX/K5OqZhjMW94b8VgmwkwEB1alotBZXa6w3uZGSuybqHKZJm+zJHy6AQINzXo8xS/QqL0zvHki7up9Y1NwmZcGefrLMtSaxhNLICsvfMgAC+RYWkBssvb/M6ASZx6e52eCxPCvodnlMzfvVNmxj4MbEWFnPHaStRSmHkieWURCm4jB40H9lMxpm+vZMjMaOYex5rC0sw62NecFTgY6rxIJaFz1gKBk3ZUclsyL1d9fGLOtRvBJZqFUSUbeMl6w= 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: c2965d39-3126-40ff-27e2-08d610d4942b X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Sep 2018 13:03:57.7249 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0135 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stefan Hajnoczi [ Upstream commit b7751410c180a05fdc21268f8661b1480169b0df ] dax_pmem_percpu_exit() waits for dax_pmem_percpu_release() to invoke the dax_pmem->cmp completion. Unfortunately this approach to cleaning up the percpu_ref only works after devm_memremap_pages() was successful. If devm_add_action_or_reset() or devm_memremap_pages() fails, dax_pmem_percpu_release() is not invoked. Therefore dax_pmem_percpu_exit() hangs waiting for the completion: rc =3D devm_add_action_or_reset(dev, dax_pmem_percpu_exit, &dax_pmem->ref); if (rc) return rc; dax_pmem->pgmap.ref =3D &dax_pmem->ref; addr =3D devm_memremap_pages(dev, &dax_pmem->pgmap); Avoid the hang by calling percpu_ref_exit() in the error paths instead of going through dax_pmem_percpu_exit(). Signed-off-by: Stefan Hajnoczi Signed-off-by: Dave Jiang Signed-off-by: Sasha Levin --- drivers/dax/pmem.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index fd49b24fd6af..99e2aace8078 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -105,15 +105,19 @@ static int dax_pmem_probe(struct device *dev) if (rc) return rc; =20 - rc =3D devm_add_action_or_reset(dev, dax_pmem_percpu_exit, - &dax_pmem->ref); - if (rc) + rc =3D devm_add_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); + if (rc) { + percpu_ref_exit(&dax_pmem->ref); return rc; + } =20 dax_pmem->pgmap.ref =3D &dax_pmem->ref; addr =3D devm_memremap_pages(dev, &dax_pmem->pgmap); - if (IS_ERR(addr)) + if (IS_ERR(addr)) { + devm_remove_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); + percpu_ref_exit(&dax_pmem->ref); return PTR_ERR(addr); + } =20 rc =3D devm_add_action_or_reset(dev, dax_pmem_percpu_kill, &dax_pmem->ref); --=20 2.17.1