3 files changed, 33 insertions, 4 deletions

diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index b56fe8b67a8..6da9ab4f5a1 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -114,6 +114,11 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
 			to_mm->id.u.pid = copy_context_skas0(stack,
 							     from_mm->id.u.pid);
 		else to_mm->id.u.pid = start_userspace(stack);
+
+		if (to_mm->id.u.pid < 0) {
+			ret = to_mm->id.u.pid;
+			goto out_free;
+		}
 	}
 
 	ret = init_new_ldt(to_mm, from_mm);
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index fce389c2342..2e9852c0d48 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -6,19 +6,25 @@
 #include "linux/init.h"
 #include "linux/sched.h"
 #include "as-layout.h"
+#include "kern.h"
 #include "os.h"
 #include "skas.h"
 
 int new_mm(unsigned long stack)
 {
-	int fd;
+	int fd, err;
 
 	fd = os_open_file("/proc/mm", of_cloexec(of_write(OPENFLAGS())), 0);
 	if (fd < 0)
 		return fd;
 
-	if (skas_needs_stub)
-		map_stub_pages(fd, STUB_CODE, STUB_DATA, stack);
+	if (skas_needs_stub) {
+		err = map_stub_pages(fd, STUB_CODE, STUB_DATA, stack);
+		if (err) {
+			os_close_file(fd);
+			return err;
+		}
+	}
 
 	return fd;
 }
@@ -49,8 +55,14 @@ int __init start_uml(void)
 {
 	stack_protections((unsigned long) &cpu0_irqstack);
 	set_sigstack(cpu0_irqstack, THREAD_SIZE);
-	if (proc_mm)
+	if (proc_mm) {
 		userspace_pid[0] = start_userspace(0);
+		if (userspace_pid[0] < 0) {
+			printf("start_uml - start_userspace returned %d\n",
+			       userspace_pid[0]);
+			exit(1);
+		}
+	}
 
 	init_new_thread_signals();
 
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 8fd1a797c3e..44e49041949 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -129,6 +129,18 @@ static void bad_segv(struct faultinfo fi, unsigned long ip)
 	force_sig_info(SIGSEGV, &si, current);
 }
 
+void fatal_sigsegv(void)
+{
+	force_sigsegv(SIGSEGV, current);
+	do_signal();
+	/*
+	 * This is to tell gcc that we're not returning - do_signal
+	 * can, in general, return, but in this case, it's not, since
+	 * we just got a fatal SIGSEGV queued.
+	 */
+	os_dump_core();
+}
+
 void segv_handler(int sig, struct uml_pt_regs *regs)
 {
 	struct faultinfo * fi = UPT_FAULTINFO(regs);