linux-kernel - Re: please fix FUSION (Was: [v3.13][v3.14][Regression] kthread:makekthread

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Message-ID: <20140319194232.GA6207@redhat.com>
Date:	Wed, 19 Mar 2014 20:42:32 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Joseph Salisbury <joseph.salisbury@...onical.com>
Cc:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	JBottomley@...allels.com, Nagalakshmi.Nandigama@....com,
	Sreekanth.Reddy@....com, rientjes@...gle.com,
	akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
	tj@...nel.org, tglx@...utronix.de, linux-kernel@...r.kernel.org,
	kernel-team@...ts.ubuntu.com, linux-scsi@...r.kernel.org
Subject: Re: please fix FUSION (Was: [v3.13][v3.14][Regression]
	kthread:makekthread_create()killable)

On 03/19, Oleg Nesterov wrote:
>
> On 03/19, Oleg Nesterov wrote:
> >
> > But please do not forget that the kernel crashes. Whatever else we do, this
> > should be fixed anyway. And this should be fixed in driver.
>
> drivers/message/fusion/ is obviously buggy.

Perhaps this is the only problem and Tetsuo is right, this driver
really needs more than 30 secs to probe...

But if you have a bit of free time, perhaps you can try the stupid
debugging patch below ;) Not sure it will help, but who knows.

Oleg.

diff --git a/drivers/message/fusion/mptsas.c b/drivers/message/fusion/mptsas.c
index 00d339c..5ecc27e 100644
--- a/drivers/message/fusion/mptsas.c
+++ b/drivers/message/fusion/mptsas.c
@@ -5400,12 +5400,16 @@ mptsas_init(void)
 {
 	int error;
 
+	printk(KERN_CRIT "mptsas_init start\n");
+	current->flags |= 0x1;
 	show_mptmod_ver(my_NAME, my_VERSION);
 
 	mptsas_transport_template =
 	    sas_attach_transport(&mptsas_transport_functions);
-	if (!mptsas_transport_template)
-		return -ENODEV;
+	if (!mptsas_transport_template) {
+		error = -ENODEV;
+		goto out;
+	}
 	mptsas_transport_template->eh_timed_out = mptsas_eh_timed_out;
 
 	mptsasDoneCtx = mpt_register(mptscsih_io_done, MPTSAS_DRIVER,
@@ -5428,6 +5432,9 @@ mptsas_init(void)
 	if (error)
 		sas_release_transport(mptsas_transport_template);
 
+out:
+	current->flags &= ~0x1;
+	printk(KERN_CRIT "mptsas_init end\n");
 	return error;
 }
 
diff --git a/kernel/kthread.c b/kernel/kthread.c
index b5ae3ee..78e643d 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -291,6 +291,13 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
 	 * the OOM killer while kthreadd is trying to allocate memory for
 	 * new kernel thread.
 	 */
+
+	if (current->flags & 1) {
+		pr_crit("mptsas no killable wait: %d %d\n",
+			signal_pending(current), __fatal_signal_pending(current));
+		goto wait;
+	}
+
 	if (unlikely(wait_for_completion_killable(&done))) {
 		/*
 		 * If I was SIGKILLed before kthreadd (or new kernel thread)
@@ -303,6 +310,7 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
 		 * kthreadd (or new kernel thread) will call complete()
 		 * shortly.
 		 */
+wait:
 		wait_for_completion(&done);
 	}
 	task = create->result;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b46131e..2b202bd 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2655,6 +2655,14 @@ static void __sched __schedule(void)
 	unsigned long *switch_count;
 	struct rq *rq;
 	int cpu;
+	bool trace;
+
+	trace = (current->flags & 1) && current->state && !(preempt_count() & PREEMPT_ACTIVE);
+	if (trace) {
+		pr_crit("mptsas sched: %lx %d %d\n", current->state,
+			signal_pending(current), __fatal_signal_pending(current));
+		show_stack(NULL, NULL);
+	}
 
 need_resched:
 	preempt_disable();
@@ -2733,6 +2741,11 @@ need_resched:
 	sched_preempt_enable_no_resched();
 	if (need_resched())
 		goto need_resched;
+
+	if (trace) {
+		pr_crit("mptsas wake: %d %d\n",
+			signal_pending(current), __fatal_signal_pending(current));
+	}
 }
 
 static inline void sched_submit_work(struct task_struct *tsk)
diff --git a/kernel/signal.c b/kernel/signal.c
index 52f881d..d121944 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1152,6 +1152,11 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
 {
 	int from_ancestor_ns = 0;
 
+	if (t->flags & 1) {
+		pr_crit("mptsas killed %d\n", sig);
+		sched_show_task(t);
+	}
+
 #ifdef CONFIG_PID_NS
 	from_ancestor_ns = si_fromuser(info) &&
 			   !task_pid_nr_ns(current, task_active_pid_ns(t));

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