[stgt] Help pinpointing cause of tgtd instability

FUJITA Tomonori fujita.tomonori at lab.ntt.co.jp
Sun Dec 4 05:18:56 CET 2011

On Thu, 1 Dec 2011 10:32:35 -0500
John Pletka <jpletka at abraxis.com> wrote:

> I have two NAS devices running an almost identical workload.  One of
> them has been perfectly stable for over a year now.  On the other,
> tgtd either aborts, or causes the iscsi mounted file systems to go
> into read-only mode about once a week.  I wanted to lay out my
> configuration to see if there is a most-likely cause.  One thing that
> stands out is the scsi-target-utils version is 1.0.4 on the unstable
> server, and 1.0.8 on the stable server.  yum update on CentOS 6 says
> 1.0.4 is the most recent though and I see patches through Jan 17,
> 2011.  Other potential causes -- bonded ethernet ports on the unstable
> one, and no swap partition on the unstable one (the OS is installed on
> a compact-flash card).
> From the abrt logs:
> Process /usr/sbin/tgtd was killed by signal 11 (SIGSEGV)
> Which <might> be related to this bug:
> https://bugzilla.redhat.com/show_bug.cgi?id=712807

I think that the above bug is not related with your problem. It's more
likely that the problem is due to task management bugs. We've not
figured out how the bugs happen.

The following patch disables tmf. Try it to see if it works for you.

diff --git a/usr/iscsi/iscsid.c b/usr/iscsi/iscsid.c
index 3fbd9f6..6b814ba 100644
--- a/usr/iscsi/iscsid.c
+++ b/usr/iscsi/iscsid.c
@@ -1405,6 +1405,9 @@ static int iscsi_tm_execute(struct iscsi_task *task)
 	struct iscsi_tm *req = (struct iscsi_tm *) &task->req;
 	int fn = 0, err = 0;
+#if 0
 	switch (req->flags & ISCSI_FLAG_TM_FUNC_MASK) {
 		fn = ABORT_TASK;
@@ -1432,7 +1435,7 @@ static int iscsi_tm_execute(struct iscsi_task *task)
 		eprintf("unknown task management function %d\n",
 			req->flags & ISCSI_FLAG_TM_FUNC_MASK);
 	if (err)
 		task->result = err;
 	else {
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