| From 2a2361228c5e6d8c1733f00653481de918598e50 Mon Sep 17 00:00:00 2001 |
| From: Thorsten Knabe <linux@thorsten-knabe.de> |
| Date: Sat, 23 Aug 2014 15:47:38 +0200 |
| Subject: um: ubd: Fix for processes stuck in D state forever |
| |
| From: Thorsten Knabe <linux@thorsten-knabe.de> |
| |
| 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 <linux@thorsten-knabe.de> |
| Signed-off-by: Richard Weinberger <richard@nod.at> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| 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){ |
