From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-sn1nam02on0123.outbound.protection.outlook.com ([104.47.36.123]:20160 "EHLO NAM02-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727989AbeIBRUD (ORCPT ); Sun, 2 Sep 2018 13:20:03 -0400 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() 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> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: 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