diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index 5cd1bd4b23ac..b087b4278173 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -20,6 +20,9 @@ obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \
 	um_arch.o umid.o kmsg_dump.o capflags.o skas/
 obj-y += load_file.o
 obj-$(CONFIG_MMU) += mem-pgtable.o tlb.o trap-mmu.o
+ifneq ($(CONFIG_MMU),y)
+obj-y += trap-nommu.o
+endif
 
 obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
 obj-$(CONFIG_GPROF)	+= gprof_syms.o
diff --git a/arch/um/kernel/skas/Makefile b/arch/um/kernel/skas/Makefile
index 28dd33580abc..c098d087c3f2 100644
--- a/arch/um/kernel/skas/Makefile
+++ b/arch/um/kernel/skas/Makefile
@@ -6,6 +6,9 @@
 obj-y := stub.o process.o syscall.o \
 	 stub_exe_embed.o
 obj-$(CONFIG_MMU) += mmu.o uaccess.o
+ifneq ($(CONFIG_MMU),y)
+obj-y += nommu.o
+endif
 
 # Stub executable
 
diff --git a/arch/um/kernel/skas/nommu.c b/arch/um/kernel/skas/nommu.c
new file mode 100644
index 000000000000..80d5c4eaa96b
--- /dev/null
+++ b/arch/um/kernel/skas/nommu.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/cpumask.h>
+#include <linux/gfp.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/mutex.h>
+#include <linux/panic.h>
+#include <linux/smp.h>
+#include <linux/threads.h>
+#include <as-layout.h>
+#include <mem.h>
+#include <os.h>
+#include <skas.h>
+#include <mm_id.h>
+
+struct nommu_runner {
+	struct mm_id mm_id;
+	struct mutex turnstile;
+};
+
+static struct nommu_runner nommu_runners[NR_CPUS];
+
+static struct nommu_runner *this_runner(void)
+{
+	return &nommu_runners[raw_smp_processor_id()];
+}
+
+struct mutex *__get_turnstile(struct mm_id *mm_id)
+{
+	return &container_of(mm_id, struct nommu_runner, mm_id)->turnstile;
+}
+
+void enter_turnstile(struct mm_id *mm_id)
+{
+	mutex_lock(__get_turnstile(mm_id));
+}
+
+void exit_turnstile(struct mm_id *mm_id)
+{
+	mutex_unlock(__get_turnstile(mm_id));
+}
+
+unsigned long current_stub_stack(void)
+{
+	return this_runner()->mm_id.stack;
+}
+
+struct mm_id *current_mm_id(void)
+{
+	return &this_runner()->mm_id;
+}
+
+void current_mm_sync(void)
+{
+}
+
+static int __init nommu_start_runners(void)
+{
+	unsigned long long offset;
+	struct nommu_runner *r;
+	int cpu, err, fd;
+
+	fd = phys_mapping(uml_reserved - uml_physmem, &offset);
+
+	for_each_possible_cpu(cpu) {
+		r = &nommu_runners[cpu];
+		mutex_init(&r->turnstile);
+
+		r->mm_id.stack = __get_free_pages(GFP_KERNEL | __GFP_ZERO,
+						  ilog2(STUB_DATA_PAGES));
+		if (!r->mm_id.stack)
+			panic("OOM allocating userspace stack for CPU %d", cpu);
+
+		err = start_userspace(&r->mm_id);
+		if (err < 0)
+			panic("userspace startup for CPU %d failed: %d",
+			      cpu, err);
+
+		map(&r->mm_id, uml_reserved, high_physmem - uml_reserved,
+		    UM_PROT_READ | UM_PROT_WRITE | UM_PROT_EXEC, fd, offset);
+
+		err = syscall_stub_flush(&r->mm_id);
+		if (err < 0)
+			panic("physmem map/flush failed for CPU%d: %d",
+			      cpu, err);
+	}
+
+	return 0;
+}
+arch_initcall(nommu_start_runners);
diff --git a/arch/um/kernel/smp.c b/arch/um/kernel/smp.c
index f1e52b7348fb..92ea1beaed8b 100644
--- a/arch/um/kernel/smp.c
+++ b/arch/um/kernel/smp.c
@@ -20,6 +20,7 @@
 #include <init.h>
 #include <kern.h>
 #include <os.h>
+#include <skas.h>
 #include <smp.h>
 
 enum {
@@ -66,7 +67,7 @@ static void ipi_handler(int vector, struct uml_pt_regs *regs)
 	irq_enter();
 
 	if (current->mm)
-		os_alarm_process(current->mm->context.id.pid);
+		os_alarm_process(current_mm_id()->pid);
 
 	switch (vector) {
 	case UML_IPI_RES:
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index b344a36b44eb..d620b6d6310a 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -19,6 +19,7 @@
 #include <asm/param.h>
 #include <kern_util.h>
 #include <os.h>
+#include <skas.h>
 #include <linux/delay.h>
 #include <linux/time-internal.h>
 #include <linux/um_timetravel.h>
@@ -873,7 +874,7 @@ static irqreturn_t um_timer(int irq, void *dev)
 	if (time_travel_mode != TT_MODE_INFCPU &&
 	    time_travel_mode != TT_MODE_EXTERNAL &&
 	    get_current()->mm)
-		os_alarm_process(get_current()->mm->context.id.pid);
+		os_alarm_process(current_mm_id()->pid);
 
 	evt->event_handler(evt);
 
diff --git a/arch/um/kernel/trap-nommu.c b/arch/um/kernel/trap-nommu.c
new file mode 100644
index 000000000000..891a9cefa935
--- /dev/null
+++ b/arch/um/kernel/trap-nommu.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <shared/kern_util.h>
+
+int handle_page_fault(unsigned long address, unsigned long ip,
+		      int is_write, int is_user, int *code_out)
+{
+	/* everything that's valid is already mapped in NOMMU */
+	*code_out = SEGV_MAPERR;
+	return -EFAULT;
+}