arch: mm: pass userspace fault flag to generic fault handler

Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.

Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

29 files changed, 135 insertions, 64 deletions

diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 0c4132d..98838a0 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -89,8 +89,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 	const struct exception_table_entry *fixup;
 	int fault, si_code = SEGV_MAPERR;
 	siginfo_t info;
-	unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-			      (cause > 0 ? FAULT_FLAG_WRITE : 0));
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	/* As of EV6, a load into $31/$f31 is a prefetch, and never faults
 	   (or is suppressed by the PALcode).  Support that for older CPUs
@@ -115,7 +114,8 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 	if (address >= TASK_SIZE)
 		goto vmalloc_fault;
 #endif
-
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
@@ -142,6 +142,7 @@ retry:
 	} else {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	}
 
 	/* If for any reason at all we couldn't handle the fault,
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 6b0bb41..d63f3de 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -60,8 +60,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address)
 	siginfo_t info;
 	int fault, ret;
 	int write = regs->ecr_cause & ECR_C_PROTV_STORE;  /* ST/EX */
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-				(write ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	/*
 	 * We fault-in kernel-space virtual memory on-demand. The
@@ -89,6 +88,8 @@ void do_page_fault(struct pt_regs *regs, unsigned long address)
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
@@ -117,6 +118,7 @@ good_area:
 	if (write) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 217bcbf..eb8830a 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -261,9 +261,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	int fault, sig, code;
-	int write = fsr & FSR_WRITE;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-				(write ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	if (notify_page_fault(regs, fsr))
 		return 0;
@@ -282,6 +280,11 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+	if (fsr & FSR_WRITE)
+		flags |= FAULT_FLAG_WRITE;
+
 	/*
 	 * As per x86, we may deadlock here.  However, since the kernel only
 	 * validly references user space from well defined areas of the code,
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 0bb7db4..6d6acf1 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -199,13 +199,6 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 	unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;
 	unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
-	if (esr & ESR_LNX_EXEC) {
-		vm_flags = VM_EXEC;
-	} else if ((esr & ESR_WRITE) && !(esr & ESR_CM)) {
-		vm_flags = VM_WRITE;
-		mm_flags |= FAULT_FLAG_WRITE;
-	}
-
 	tsk = current;
 	mm  = tsk->mm;
 
@@ -220,6 +213,16 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		mm_flags |= FAULT_FLAG_USER;
+
+	if (esr & ESR_LNX_EXEC) {
+		vm_flags = VM_EXEC;
+	} else if ((esr & ESR_WRITE) && !(esr & ESR_CM)) {
+		vm_flags = VM_WRITE;
+		mm_flags |= FAULT_FLAG_WRITE;
+	}
+
 	/*
 	 * As per x86, we may deadlock here. However, since the kernel only
 	 * validly references user space from well defined areas of the code,
diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index 2ca27b0..0eca933 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -86,6 +86,8 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 
 	local_irq_enable();
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 
diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index 73312ab..1790f22 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -58,8 +58,7 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
 	struct vm_area_struct * vma;
 	siginfo_t info;
 	int fault;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-				((writeaccess & 1) ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	D(printk(KERN_DEBUG
 		 "Page fault for %lX on %X at %lX, prot %d write %d\n",
@@ -117,6 +116,8 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
@@ -155,6 +156,7 @@ retry:
 	} else if (writeaccess == 1) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c
index 331c1e2..9a66372 100644
--- a/arch/frv/mm/fault.c
+++ b/arch/frv/mm/fault.c
@@ -34,11 +34,11 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 	struct vm_area_struct *vma;
 	struct mm_struct *mm;
 	unsigned long _pme, lrai, lrad, fixup;
+	unsigned long flags = 0;
 	siginfo_t info;
 	pgd_t *pge;
 	pud_t *pue;
 	pte_t *pte;
-	int write;
 	int fault;
 
 #if 0
@@ -81,6 +81,9 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(__frame))
+		flags |= FAULT_FLAG_USER;
+
 	down_read(&mm->mmap_sem);
 
 	vma = find_vma(mm, ear0);
@@ -129,7 +132,6 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
  */
  good_area:
 	info.si_code = SEGV_ACCERR;
-	write = 0;
 	switch (esr0 & ESR0_ATXC) {
 	default:
 		/* handle write to write protected page */
@@ -140,7 +142,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 #endif
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
-		write = 1;
+		flags |= FAULT_FLAG_WRITE;
 		break;
 
 		 /* handle read from protected page */
@@ -162,7 +164,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, ear0, write ? FAULT_FLAG_WRITE : 0);
+	fault = handle_mm_fault(mm, vma, ear0, flags);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
index 1bd276d..8704c93 100644
--- a/arch/hexagon/mm/vm_fault.c
+++ b/arch/hexagon/mm/vm_fault.c
@@ -53,8 +53,7 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
 	int si_code = SEGV_MAPERR;
 	int fault;
 	const struct exception_table_entry *fixup;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-				 (cause > 0 ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	/*
 	 * If we're in an interrupt or have no user context,
@@ -65,6 +64,8 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
 
 	local_irq_enable();
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
@@ -96,6 +97,7 @@ good_area:
 	case FLT_STORE:
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 		break;
 	}
 
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 6cf0341..7225dad 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -90,8 +90,6 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
 	mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
 		| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
 
-	flags |= ((mask & VM_WRITE) ? FAULT_FLAG_WRITE : 0);
-
 	/* mmap_sem is performance critical.... */
 	prefetchw(&mm->mmap_sem);
 
@@ -119,6 +117,10 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
 	if (notify_page_fault(regs, TRAP_BRKPT))
 		return;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+	if (mask & VM_WRITE)
+		flags |= FAULT_FLAG_WRITE;
 retry:
 	down_read(&mm->mmap_sem);
 
diff --git a/arch/m32r/mm/fault.c b/arch/m32r/mm/fault.c
index 3cdfa9c..e9c6a80 100644
--- a/arch/m32r/mm/fault.c
+++ b/arch/m32r/mm/fault.c
@@ -78,7 +78,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
 	unsigned long page, addr;
-	int write;
+	unsigned long flags = 0;
 	int fault;
 	siginfo_t info;
 
@@ -117,6 +117,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
 	if (in_atomic() || !mm)
 		goto bad_area_nosemaphore;
 
+	if (error_code & ACE_USERMODE)
+		flags |= FAULT_FLAG_USER;
+
 	/* When running in the kernel we expect faults to occur only to
 	 * addresses in user space.  All other faults represent errors in the
 	 * kernel and should generate an OOPS.  Unfortunately, in the case of an
@@ -166,14 +169,13 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
  */
 good_area:
 	info.si_code = SEGV_ACCERR;
-	write = 0;
 	switch (error_code & (ACE_WRITE|ACE_PROTECTION)) {
 		default:	/* 3: write, present */
 			/* fall through */
 		case ACE_WRITE:	/* write, not present */
 			if (!(vma->vm_flags & VM_WRITE))
 				goto bad_area;
-			write++;
+			flags |= FAULT_FLAG_WRITE;
 			break;
 		case ACE_PROTECTION:	/* read, present */
 		case 0:		/* read, not present */
@@ -194,7 +196,7 @@ good_area:
 	 */
 	addr = (address & PAGE_MASK);
 	set_thread_fault_code(error_code);
-	fault = handle_mm_fault(mm, vma, addr, write ? FAULT_FLAG_WRITE : 0);
+	fault = handle_mm_fault(mm, vma, addr, flags);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index a563727..eb1d61f 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -88,6 +88,8 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 
diff --git a/arch/metag/mm/fault.c b/arch/metag/mm/fault.c
index 8fddf46..332680e 100644
--- a/arch/metag/mm/fault.c
+++ b/arch/metag/mm/fault.c
@@ -53,8 +53,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	struct vm_area_struct *vma, *prev_vma;
 	siginfo_t info;
 	int fault;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-				(write_access ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	tsk = current;
 
@@ -109,6 +108,8 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 
@@ -121,6 +122,7 @@ good_area:
 	if (write_access) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 			goto bad_area;
diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index 731f739..fa4cf52 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -92,8 +92,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
 	int code = SEGV_MAPERR;
 	int is_write = error_code & ESR_S;
 	int fault;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-					 (is_write ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	regs->ear = address;
 	regs->esr = error_code;
@@ -121,6 +120,9 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
 		die("Weird page fault", regs, SIGSEGV);
 	}
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+
 	/* When running in the kernel we expect faults to occur only to
 	 * addresses in user space.  All other faults represent errors in the
 	 * kernel and should generate an OOPS.  Unfortunately, in the case of an
@@ -199,6 +201,7 @@ good_area:
 	if (unlikely(is_write)) {
 		if (unlikely(!(vma->vm_flags & VM_WRITE)))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	/* a read */
 	} else {
 		/* protection fault */
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 94d3a31..becc42b 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -42,8 +42,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
 	const int field = sizeof(unsigned long) * 2;
 	siginfo_t info;
 	int fault;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-						 (write ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 #if 0
 	printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
@@ -93,6 +92,8 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
 	if (in_atomic() || !mm)
 		goto bad_area_nosemaphore;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
@@ -114,6 +115,7 @@ good_area:
 	if (write) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		if (cpu_has_rixi) {
 			if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
diff --git a/arch/mn10300/mm/fault.c b/arch/mn10300/mm/fault.c
index 8a2e6de..3516cbd 100644
--- a/arch/mn10300/mm/fault.c
+++ b/arch/mn10300/mm/fault.c
@@ -171,6 +171,8 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 
diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 4a41f84..0703acf 100644
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c
@@ -86,6 +86,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
 	if (user_mode(regs)) {
 		/* Exception was in userspace: reenable interrupts */
 		local_irq_enable();
+		flags |= FAULT_FLAG_USER;
 	} else {
 		/* If exception was in a syscall, then IRQ's may have
 		 * been enabled or disabled.  If they were enabled,
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index f247a34..d10d27a 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -180,6 +180,10 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+	if (acc_type & VM_WRITE)
+		flags |= FAULT_FLAG_WRITE;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma_prev(mm, address, &prev_vma);
@@ -203,8 +207,7 @@ good_area:
 	 * fault.
 	 */
 
-	fault = handle_mm_fault(mm, vma, address,
-			flags | ((acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0));
+	fault = handle_mm_fault(mm, vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 		return;
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 2dd69bf..51ab9e7 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -223,9 +223,6 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
 	is_write = error_code & ESR_DST;
 #endif /* CONFIG_4xx || CONFIG_BOOKE */
 
-	if (is_write)
-		flags |= FAULT_FLAG_WRITE;
-
 #ifdef CONFIG_PPC_ICSWX
 	/*
 	 * we need to do this early because this "data storage
@@ -288,6 +285,9 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
 	if (user_mode(regs))
 		store_update_sp = store_updates_sp(regs);
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+
 	/* When running in the kernel we expect faults to occur only to
 	 * addresses in user space.  All other faults represent errors in the
 	 * kernel and should generate an OOPS.  Unfortunately, in the case of an
@@ -415,6 +415,7 @@ good_area:
 	} else if (is_write) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	/* a read */
 	} else {
 		/* protection fault */
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 7de4469..fc66792 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -302,6 +302,8 @@ static inline int do_exception(struct pt_regs *regs, int access)
 	address = trans_exc_code & __FAIL_ADDR_MASK;
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 	flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 	if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
 		flags |= FAULT_FLAG_WRITE;
 	down_read(&mm->mmap_sem);
diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c
index 4b71a62..52238983 100644
--- a/arch/score/mm/fault.c
+++ b/arch/score/mm/fault.c
@@ -47,6 +47,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
 	const int field = sizeof(unsigned long) * 2;
+	unsigned long flags = 0;
 	siginfo_t info;
 	int fault;
 
@@ -75,6 +76,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
 	if (in_atomic() || !mm)
 		goto bad_area_nosemaphore;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
 	if (!vma)
@@ -95,6 +99,7 @@ good_area:
 	if (write) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 			goto bad_area;
@@ -105,7 +110,7 @@ good_area:
 	* make sure we exit gracefully rather than endlessly redo
 	* the fault.
 	*/
-	fault = handle_mm_fault(mm, vma, address, write);
+	fault = handle_mm_fault(mm, vma, address, flags);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 1f49c28a..541dc61 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -400,9 +400,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
 	int fault;
-	int write = error_code & FAULT_CODE_WRITE;
-	unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-			      (write ? FAULT_FLAG_WRITE : 0));
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	tsk = current;
 	mm = tsk->mm;
@@ -476,6 +474,11 @@ good_area:
 
 	set_thread_fault_code(error_code);
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+	if (error_code & FAULT_CODE_WRITE)
+		flags |= FAULT_FLAG_WRITE;
+
 	/*
 	 * If for any reason at all we couldn't handle the fault,
 	 * make sure we exit gracefully rather than endlessly redo
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index e98bfda..59dbd46 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -177,8 +177,7 @@ asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 	unsigned long g2;
 	int from_user = !(regs->psr & PSR_PS);
 	int fault, code;
-	unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-			      (write ? FAULT_FLAG_WRITE : 0));
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	if (text_fault)
 		address = regs->pc;
@@ -235,6 +234,11 @@ good_area:
 			goto bad_area;
 	}
 
+	if (from_user)
+		flags |= FAULT_FLAG_USER;
+	if (write)
+		flags |= FAULT_FLAG_WRITE;
+
 	/*
 	 * If for any reason at all we couldn't handle the fault,
 	 * make sure we exit gracefully rather than endlessly redo
@@ -383,6 +387,7 @@ static void force_user_fault(unsigned long address, int write)
 	struct vm_area_struct *vma;
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
+	unsigned int flags = FAULT_FLAG_USER;
 	int code;
 
 	code = SEGV_MAPERR;
@@ -402,11 +407,12 @@ good_area:
 	if (write) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}
-	switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
+	switch (handle_mm_fault(mm, vma, address, flags)) {
 	case VM_FAULT_SIGBUS:
 	case VM_FAULT_OOM:
 		goto do_sigbus;
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 5062ff3..2ebec26 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -315,7 +315,8 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 			bad_kernel_pc(regs, address);
 			return;
 		}
-	}
+	} else
+		flags |= FAULT_FLAG_USER;
 
 	/*
 	 * If we're in an interrupt or have no user
@@ -418,13 +419,14 @@ good_area:
 		    vma->vm_file != NULL)
 			set_thread_fault_code(fault_code |
 					      FAULT_CODE_BLKCOMMIT);
+
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		/* Allow reads even for write-only mappings */
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}
 
-	flags |= ((fault_code & FAULT_CODE_WRITE) ? FAULT_FLAG_WRITE : 0);
 	fault = handle_mm_fault(mm, vma, address, flags);
 
 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 4fd2c0f..4c288f1 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -280,8 +280,7 @@ static int handle_page_fault(struct pt_regs *regs,
 	if (!is_page_fault)
 		write = 1;
 
-	flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-		 (write ? FAULT_FLAG_WRITE : 0));
+	flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	is_kernel_mode = !user_mode(regs);
 
@@ -365,6 +364,9 @@ static int handle_page_fault(struct pt_regs *regs,
 		goto bad_area_nosemaphore;
 	}
 
+	if (!is_kernel_mode)
+		flags |= FAULT_FLAG_USER;
+
 	/*
 	 * When running in the kernel we expect faults to occur only to
 	 * addresses in user space.  All other faults represent errors in the
@@ -425,6 +427,7 @@ good_area:
 #endif
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
+		flags |= FAULT_FLAG_WRITE;
 	} else {
 		if (!is_page_fault || !(vma->vm_flags & VM_READ))
 			goto bad_area;
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index b2f5adf..5c3aef7 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -30,8 +30,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
 	pmd_t *pmd;
 	pte_t *pte;
 	int err = -EFAULT;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-				 (is_write ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	*code_out = SEGV_MAPERR;
 
@@ -42,6 +41,8 @@ int handle_page_fault(unsigned long address, unsigned long ip,
 	if (in_atomic())
 		goto out_nosemaphore;
 
+	if (is_user)
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
@@ -58,12 +59,15 @@ retry:
 
 good_area:
 	*code_out = SEGV_ACCERR;
-	if (is_write && !(vma->vm_flags & VM_WRITE))
-		goto out;
-
-	/* Don't require VM_READ|VM_EXEC for write faults! */
-	if (!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
-		goto out;
+	if (is_write) {
+		if (!(vma->vm_flags & VM_WRITE))
+			goto out;
+		flags |= FAULT_FLAG_WRITE;
+	} else {
+		/* Don't require VM_READ|VM_EXEC for write faults! */
+		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+			goto out;
+	}
 
 	do {
 		int fault;
diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
index 8ed3c45..0dc922d 100644
--- a/arch/unicore32/mm/fault.c
+++ b/arch/unicore32/mm/fault.c
@@ -209,8 +209,7 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	int fault, sig, code;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-				 ((!(fsr ^ 0x12)) ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	tsk = current;
 	mm = tsk->mm;
@@ -222,6 +221,11 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+	if (!(fsr ^ 0x12))
+		flags |= FAULT_FLAG_WRITE;
+
 	/*
 	 * As per x86, we may deadlock here.  However, since the kernel only
 	 * validly references user space from well defined areas of the code,
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 654be4a..6d77c38 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1011,9 +1011,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
 	unsigned long address;
 	struct mm_struct *mm;
 	int fault;
-	int write = error_code & PF_WRITE;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
-					(write ? FAULT_FLAG_WRITE : 0);
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	tsk = current;
 	mm = tsk->mm;
@@ -1083,6 +1081,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
 	if (user_mode_vm(regs)) {
 		local_irq_enable();
 		error_code |= PF_USER;
+		flags |= FAULT_FLAG_USER;
 	} else {
 		if (regs->flags & X86_EFLAGS_IF)
 			local_irq_enable();
@@ -1109,6 +1108,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
 		return;
 	}
 
+	if (error_code & PF_WRITE)
+		flags |= FAULT_FLAG_WRITE;
+
 	/*
 	 * When running in the kernel we expect faults to occur only to
 	 * addresses in user space.  All other faults represent errors in
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index 4b7bc8d..70fa7bc 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -72,6 +72,8 @@ void do_page_fault(struct pt_regs *regs)
 	       address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
 #endif
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index caf543c..3d9b503 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -176,6 +176,7 @@ extern pgprot_t protection_map[16];
 #define FAULT_FLAG_RETRY_NOWAIT	0x10	/* Don't drop mmap_sem and wait when retrying */
 #define FAULT_FLAG_KILLABLE	0x20	/* The fault task is in SIGKILL killable region */
 #define FAULT_FLAG_TRIED	0x40	/* second try */
+#define FAULT_FLAG_USER		0x80	/* The fault originated in userspace */
 
 /*
  * vm_fault is filled by the the pagefault handler and passed to the vma's