[3.16.y-ckt stable] Patch "um: ubd: Fix for processes stuck in D state forever" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Mon Nov 17 11:16:39 UTC 2014
This is a note to let you know that I have just added a patch titled
um: ubd: Fix for processes stuck in D state forever
to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue
This patch is scheduled to be released in version 3.16.7-ckt2.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From b9256513ba99ff64e0041186563c870ee166cf44 Mon Sep 17 00:00:00 2001
From: Thorsten Knabe <linux at thorsten-knabe.de>
Date: Sat, 23 Aug 2014 15:47:38 +0200
Subject: um: ubd: Fix for processes stuck in D state forever
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 at thorsten-knabe.de>
Signed-off-by: Richard Weinberger <richard at nod.at>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
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 3716e6952554..e8ab93c3e638 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){
--
2.1.0
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