From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thorsten Knabe , Richard Weinberger Subject: [PATCH 3.14 044/203] um: ubd: Fix for processes stuck in D state forever Date: Wed, 12 Nov 2014 10:15:14 +0900 Message-Id: <20141112011544.735783628@linuxfoundation.org> In-Reply-To: <20141112011542.686743533@linuxfoundation.org> References: <20141112011542.686743533@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.14-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: Greg Kroah-Hartman --- arch/um/drivers/ubd_kern.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -1277,7 +1277,7 @@ static void do_ubd_request(struct reques 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 reques 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){