From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753253AbaJ0TCs (ORCPT ); Mon, 27 Oct 2014 15:02:48 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52625 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752164AbaJ0TCq (ORCPT ); Mon, 27 Oct 2014 15:02:46 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Thorsten Knabe , Richard Weinberger , Kamal Mostafa Subject: [PATCH 3.13 092/105] um: ubd: Fix for processes stuck in D state forever Date: Mon, 27 Oct 2014 11:57:07 -0700 Message-Id: <1414436240-13879-93-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1414436240-13879-1-git-send-email-kamal@canonical.com> References: <1414436240-13879-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Thorsten Knabe commit 2a2361228c5e6d8c1733f00653481de918598e50 upstream. Starting with Linux 3.12 processes get stuck in D state forever in UserModeLinux under sync heavy workloads. This bug was introduced by commit 805f11a0d5 (um: ubd: Add REQ_FLUSH suppport). Fix bug by adding a check if FLUSH request was successfully submitted to the I/O thread and keeping the FLUSH request on the request queue on submission failures. Fixes: 805f11a0d5 (um: ubd: Add REQ_FLUSH suppport) Signed-off-by: Thorsten Knabe Signed-off-by: Richard Weinberger Signed-off-by: Kamal Mostafa --- arch/um/drivers/ubd_kern.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c index 3716e69..e8ab93c 100644 --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -1277,7 +1277,7 @@ static void do_ubd_request(struct request_queue *q) while(1){ struct ubd *dev = q->queuedata; - if(dev->end_sg == 0){ + if(dev->request == NULL){ struct request *req = blk_fetch_request(q); if(req == NULL) return; @@ -1299,7 +1299,8 @@ static void do_ubd_request(struct request_queue *q) return; } prepare_flush_request(req, io_req); - submit_request(io_req, dev); + if (submit_request(io_req, dev) == false) + return; } while(dev->start_sg < dev->end_sg){ -- 1.9.1