diff --git a/arch/s390/include/asm/compat.h b/arch/s390/include/asm/compat.h
index de065b32381a..01a08020bc0e 100644
--- a/arch/s390/include/asm/compat.h
+++ b/arch/s390/include/asm/compat.h
@@ -5,6 +5,7 @@
  */
 #include <linux/types.h>
 #include <linux/sched.h>
+#include <linux/thread_info.h>
 
 #define PSW32_MASK_PER		0x40000000UL
 #define PSW32_MASK_DAT		0x04000000UL
@@ -163,12 +164,28 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
 	return (u32)(unsigned long)uptr;
 }
 
+#ifdef CONFIG_COMPAT
+
+static inline int is_compat_task(void)
+{
+	return test_thread_flag(TIF_31BIT);
+}
+
+#else
+
+static inline int is_compat_task(void)
+{
+	return 0;
+}
+
+#endif
+
 static inline void __user *compat_alloc_user_space(long len)
 {
 	unsigned long stack;
 
 	stack = KSTK_ESP(current);
-	if (test_thread_flag(TIF_31BIT))
+	if (is_compat_task())
 		stack &= 0x7fffffffUL;
 	return (void __user *) (stack - len);
 }
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index a3acd8e60aff..355f7a30c3f1 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -32,6 +32,7 @@
 #include <linux/elfcore.h>
 #include <linux/kernel_stat.h>
 #include <linux/syscalls.h>
+#include <asm/compat.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -204,7 +205,7 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 	save_fp_regs(&p->thread.fp_regs);
 	/* Set a new TLS ?  */
 	if (clone_flags & CLONE_SETTLS) {
-		if (test_thread_flag(TIF_31BIT)) {
+		if (is_compat_task()) {
 			p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 		} else {
 			p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 75c496f4f16d..99eef179e903 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -36,7 +36,7 @@
 #include <linux/elf.h>
 #include <linux/regset.h>
 #include <linux/tracehook.h>
-
+#include <linux/compat.h>
 #include <asm/segment.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -69,7 +69,7 @@ FixPerRegisters(struct task_struct *task)
 	if (per_info->single_step) {
 		per_info->control_regs.bits.starting_addr = 0;
 #ifdef CONFIG_COMPAT
-		if (test_thread_flag(TIF_31BIT))
+		if (is_compat_task())
 			per_info->control_regs.bits.ending_addr = 0x7fffffffUL;
 		else
 #endif
@@ -482,8 +482,7 @@ static int peek_user_compat(struct task_struct *child,
 {
 	__u32 tmp;
 
-	if (!test_thread_flag(TIF_31BIT) ||
-	    (addr & 3) || addr > sizeof(struct user) - 3)
+	if (!is_compat_task() || (addr & 3) || addr > sizeof(struct user) - 3)
 		return -EIO;
 
 	tmp = __peek_user_compat(child, addr);
@@ -584,8 +583,7 @@ static int __poke_user_compat(struct task_struct *child,
 static int poke_user_compat(struct task_struct *child,
 			    addr_t addr, addr_t data)
 {
-	if (!test_thread_flag(TIF_31BIT) ||
-	    (addr & 3) || addr > sizeof(struct user32) - 3)
+	if (!is_compat_task() || (addr & 3) || addr > sizeof(struct user32) - 3)
 		return -EIO;
 
 	return __poke_user_compat(child, addr, data);
@@ -660,7 +658,7 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 	}
 
 	if (unlikely(current->audit_context))
-		audit_syscall_entry(test_thread_flag(TIF_31BIT) ?
+		audit_syscall_entry(is_compat_task() ?
 					AUDIT_ARCH_S390 : AUDIT_ARCH_S390X,
 				    regs->gprs[2], regs->orig_gpr2,
 				    regs->gprs[3], regs->gprs[4],
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 3cf74c3ccb69..062bd64e65fa 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -26,6 +26,7 @@
 #include <linux/binfmts.h>
 #include <linux/tracehook.h>
 #include <linux/syscalls.h>
+#include <linux/compat.h>
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>
 #include <asm/lowcore.h>
@@ -482,7 +483,7 @@ void do_signal(struct pt_regs *regs)
 		/* Whee!  Actually deliver the signal.  */
 		int ret;
 #ifdef CONFIG_COMPAT
-		if (test_thread_flag(TIF_31BIT)) {
+		if (is_compat_task()) {
 			ret = handle_signal32(signr, &ka, &info, oldset, regs);
 	        }
 		else
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 7b76ee4fb16c..45e1708b70fd 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -22,7 +22,7 @@
 #include <linux/elf.h>
 #include <linux/security.h>
 #include <linux/bootmem.h>
-
+#include <linux/compat.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
 #include <asm/processor.h>
@@ -214,7 +214,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	vdso_pagelist = vdso64_pagelist;
 	vdso_pages = vdso64_pages;
 #ifdef CONFIG_COMPAT
-	if (test_thread_flag(TIF_31BIT)) {
+	if (is_compat_task()) {
 		vdso_pagelist = vdso32_pagelist;
 		vdso_pages = vdso32_pages;
 	}
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 833e8366c351..220a152c836c 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -19,6 +19,7 @@
 #include <linux/ptrace.h>
 #include <linux/mman.h>
 #include <linux/mm.h>
+#include <linux/compat.h>
 #include <linux/smp.h>
 #include <linux/kdebug.h>
 #include <linux/smp_lock.h>
@@ -239,7 +240,7 @@ static int signal_return(struct mm_struct *mm, struct pt_regs *regs,
 	up_read(&mm->mmap_sem);
 	clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
 #ifdef CONFIG_COMPAT
-	compat = test_tsk_thread_flag(current, TIF_31BIT);
+	compat = is_compat_task();
 	if (compat && instruction == 0x0a77)
 		sys32_sigreturn();
 	else if (compat && instruction == 0x0aad)
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index e008d236cc15..f4558ccf02b9 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -28,6 +28,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <asm/pgalloc.h>
+#include <asm/compat.h>
 
 /*
  * Top of mmap area (just below the process stack).
@@ -55,7 +56,7 @@ static inline int mmap_is_legacy(void)
 	/*
 	 * Force standard allocation for 64 bit programs.
 	 */
-	if (!test_thread_flag(TIF_31BIT))
+	if (!is_compat_task())
 		return 1;
 #endif
 	return sysctl_legacy_va_layout ||
@@ -91,7 +92,7 @@ EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
 
 int s390_mmap_check(unsigned long addr, unsigned long len)
 {
-	if (!test_thread_flag(TIF_31BIT) &&
+	if (!is_compat_task() &&
 	    len >= TASK_SIZE && TASK_SIZE < (1UL << 53))
 		return crst_table_upgrade(current->mm, 1UL << 53);
 	return 0;
@@ -108,8 +109,7 @@ s390_get_unmapped_area(struct file *filp, unsigned long addr,
 	area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 	if (!(area & ~PAGE_MASK))
 		return area;
-	if (area == -ENOMEM &&
-	    !test_thread_flag(TIF_31BIT) && TASK_SIZE < (1UL << 53)) {
+	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 		/* Upgrade the page table to 4 levels and retry. */
 		rc = crst_table_upgrade(mm, 1UL << 53);
 		if (rc)
@@ -131,8 +131,7 @@ s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 	area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 	if (!(area & ~PAGE_MASK))
 		return area;
-	if (area == -ENOMEM &&
-	    !test_thread_flag(TIF_31BIT) && TASK_SIZE < (1UL << 53)) {
+	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
 		/* Upgrade the page table to 4 levels and retry. */
 		rc = crst_table_upgrade(mm, 1UL << 53);
 		if (rc)