diff --git a/arch/arm/lib/backtrace.S b/arch/arm/lib/backtrace.S
index 1d5210eb4776edcacb44cb0b5a23ea91864b87c3..582925238d65ea261cc126078462ce2a66421549 100644
--- a/arch/arm/lib/backtrace.S
+++ b/arch/arm/lib/backtrace.S
@@ -66,7 +66,7 @@ for_each_frame:	tst	frame, mask		@ Check for address exceptions
 
 1003:		ldr	r2, [sv_pc, #-4]	@ if stmfd sp!, {args} exists,
 		ldr	r3, .Ldsi+4		@ adjust saved 'pc' back one
-		teq	r3, r2, lsr #10		@ instruction
+		teq	r3, r2, lsr #11		@ instruction
 		subne	r0, sv_pc, #4		@ allow for mov
 		subeq	r0, sv_pc, #8		@ allow for mov + stmia
 
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 16d373d587c476e3caf81e43f61b5fc325ffa9a4..b4be3baa83d4d284e96c8f29ff84266473b234bb 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -175,6 +175,11 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
 #ifdef CONFIG_HAVE_ARCH_PFN_VALID
 int pfn_valid(unsigned long pfn)
 {
+	phys_addr_t addr = __pfn_to_phys(pfn);
+
+	if (__phys_to_pfn(addr) != pfn)
+		return 0;
+
 	return memblock_is_map_memory(__pfn_to_phys(pfn));
 }
 EXPORT_SYMBOL(pfn_valid);
@@ -628,7 +633,8 @@ static void update_sections_early(struct section_perm perms[], int n)
 		if (t->flags & PF_KTHREAD)
 			continue;
 		for_each_thread(t, s)
-			set_section_perms(perms, n, true, s->mm);
+			if (s->mm)
+				set_section_perms(perms, n, true, s->mm);
 	}
 	set_section_perms(perms, n, true, current->active_mm);
 	set_section_perms(perms, n, true, &init_mm);