diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 31c47d0..cbeae57 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1282,11 +1282,11 @@
 
 #define SAVED_CMDLINES_DEFAULT 128
 #define NO_CMDLINE_MAP UINT_MAX
-static unsigned saved_tgids[SAVED_CMDLINES_DEFAULT];
 static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 struct saved_cmdlines_buffer {
 	unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
 	unsigned *map_cmdline_to_pid;
+	unsigned *map_cmdline_to_tgid;
 	unsigned cmdline_num;
 	int cmdline_idx;
 	char *saved_cmdlines;
@@ -1320,12 +1320,23 @@
 		return -ENOMEM;
 	}
 
+	s->map_cmdline_to_tgid = kmalloc_array(val,
+					       sizeof(*s->map_cmdline_to_tgid),
+					       GFP_KERNEL);
+	if (!s->map_cmdline_to_tgid) {
+		kfree(s->map_cmdline_to_pid);
+		kfree(s->saved_cmdlines);
+		return -ENOMEM;
+	}
+
 	s->cmdline_idx = 0;
 	s->cmdline_num = val;
 	memset(&s->map_pid_to_cmdline, NO_CMDLINE_MAP,
 	       sizeof(s->map_pid_to_cmdline));
 	memset(s->map_cmdline_to_pid, NO_CMDLINE_MAP,
 	       val * sizeof(*s->map_cmdline_to_pid));
+	memset(s->map_cmdline_to_tgid, NO_CMDLINE_MAP,
+	       val * sizeof(*s->map_cmdline_to_tgid));
 
 	return 0;
 }
@@ -1491,14 +1502,17 @@
 	if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
 		return 0;
 
+	preempt_disable();
 	/*
 	 * It's not the end of the world if we don't get
 	 * the lock, but we also don't want to spin
 	 * nor do we want to disable interrupts,
 	 * so if we miss here, then better luck next time.
 	 */
-	if (!arch_spin_trylock(&trace_cmdline_lock))
+	if (!arch_spin_trylock(&trace_cmdline_lock)) {
+		preempt_enable();
 		return 0;
+	}
 
 	idx = savedcmd->map_pid_to_cmdline[tsk->pid];
 	if (idx == NO_CMDLINE_MAP) {
@@ -1521,8 +1535,9 @@
 	}
 
 	set_cmdline(idx, tsk->comm);
-	saved_tgids[idx] = tsk->tgid;
+	savedcmd->map_cmdline_to_tgid[idx] = tsk->tgid;
 	arch_spin_unlock(&trace_cmdline_lock);
+	preempt_enable();
 
 	return 1;
 }
@@ -1564,19 +1579,29 @@
 	preempt_enable();
 }
 
-int trace_find_tgid(int pid)
+static int __find_tgid_locked(int pid)
 {
 	unsigned map;
 	int tgid;
 
-	preempt_disable();
-	arch_spin_lock(&trace_cmdline_lock);
 	map = savedcmd->map_pid_to_cmdline[pid];
 	if (map != NO_CMDLINE_MAP)
-		tgid = saved_tgids[map];
+		tgid = savedcmd->map_cmdline_to_tgid[map];
 	else
 		tgid = -1;
 
+	return tgid;
+}
+
+int trace_find_tgid(int pid)
+{
+	int tgid;
+
+	preempt_disable();
+	arch_spin_lock(&trace_cmdline_lock);
+
+	tgid = __find_tgid_locked(pid);
+
 	arch_spin_unlock(&trace_cmdline_lock);
 	preempt_enable();
 
@@ -3877,10 +3902,15 @@
 {
 	char buf[64];
 	int r;
+	unsigned int n;
 
+	preempt_disable();
 	arch_spin_lock(&trace_cmdline_lock);
-	r = scnprintf(buf, sizeof(buf), "%u\n", savedcmd->cmdline_num);
+	n = savedcmd->cmdline_num;
 	arch_spin_unlock(&trace_cmdline_lock);
+	preempt_enable();
+
+	r = scnprintf(buf, sizeof(buf), "%u\n", n);
 
 	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
@@ -3889,6 +3919,7 @@
 {
 	kfree(s->saved_cmdlines);
 	kfree(s->map_cmdline_to_pid);
+	kfree(s->map_cmdline_to_tgid);
 	kfree(s);
 }
 
@@ -3905,10 +3936,12 @@
 		return -ENOMEM;
 	}
 
+	preempt_disable();
 	arch_spin_lock(&trace_cmdline_lock);
 	savedcmd_temp = savedcmd;
 	savedcmd = s;
 	arch_spin_unlock(&trace_cmdline_lock);
+	preempt_enable();
 	free_saved_cmdlines_buffer(savedcmd_temp);
 
 	return 0;
@@ -3951,33 +3984,61 @@
 	char *file_buf;
 	char *buf;
 	int len = 0;
-	int pid;
 	int i;
+	int *pids;
+	int n = 0;
 
-	file_buf = kmalloc(SAVED_CMDLINES_DEFAULT*(16+1+16), GFP_KERNEL);
-	if (!file_buf)
+	preempt_disable();
+	arch_spin_lock(&trace_cmdline_lock);
+
+	pids = kmalloc_array(savedcmd->cmdline_num, 2*sizeof(int), GFP_KERNEL);
+	if (!pids) {
+		arch_spin_unlock(&trace_cmdline_lock);
+		preempt_enable();
 		return -ENOMEM;
+	}
 
-	buf = file_buf;
-
-	for (i = 0; i < SAVED_CMDLINES_DEFAULT; i++) {
-		int tgid;
-		int r;
+	for (i = 0; i < savedcmd->cmdline_num; i++) {
+		int pid;
 
 		pid = savedcmd->map_cmdline_to_pid[i];
 		if (pid == -1 || pid == NO_CMDLINE_MAP)
 			continue;
 
-		tgid = trace_find_tgid(pid);
-		r = sprintf(buf, "%d %d\n", pid, tgid);
+		pids[n] = pid;
+		pids[n+1] = __find_tgid_locked(pid);
+		n += 2;
+	}
+	arch_spin_unlock(&trace_cmdline_lock);
+	preempt_enable();
+
+	if (n == 0) {
+		kfree(pids);
+		return 0;
+	}
+
+	/* enough to hold max pair of pids + space, lr and nul */
+	len = n * 12;
+	file_buf = kmalloc(len, GFP_KERNEL);
+	if (!file_buf) {
+		kfree(pids);
+		return -ENOMEM;
+	}
+
+	buf = file_buf;
+	for (i = 0; i < n && len > 0; i += 2) {
+		int r;
+
+		r = snprintf(buf, len, "%d %d\n", pids[i], pids[i+1]);
 		buf += r;
-		len += r;
+		len -= r;
 	}
 
 	len = simple_read_from_buffer(ubuf, cnt, ppos,
-				      file_buf, len);
+				      file_buf, buf - file_buf);
 
 	kfree(file_buf);
+	kfree(pids);
 
 	return len;
 }