mm: fault feedback #2

This patch completes Linus's wish that the fault return codes be made into
bit flags, which I agree makes everything nicer.  This requires requires
all handle_mm_fault callers to be modified (possibly the modifications
should go further and do things like fault accounting in handle_mm_fault --
however that would be for another patch).

[akpm@linux-foundation.org: fix alpha build]
[akpm@linux-foundation.org: fix s390 build]
[akpm@linux-foundation.org: fix sparc build]
[akpm@linux-foundation.org: fix sparc64 build]
[akpm@linux-foundation.org: fix ia64 build]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Still apparently needs some ARM and PPC loving - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/alpha/mm/fault.c

@@ -148,21 +148,17 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 	   the fault.  */
 	fault = handle_mm_fault(mm, vma, address, cause > 0);
 	up_read(&mm->mmap_sem);
-
-	switch (fault) {
-	      case VM_FAULT_MINOR:
-		current->min_flt++;
-		break;
-	      case VM_FAULT_MAJOR:
-		current->maj_flt++;
-		break;
-	      case VM_FAULT_SIGBUS:
-		goto do_sigbus;
-	      case VM_FAULT_OOM:
-		goto out_of_memory;
-	      default:
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
+			goto out_of_memory;
+		else if (fault & VM_FAULT_SIGBUS)
+			goto do_sigbus;
 		BUG();
 	}
+	if (fault & VM_FAULT_MAJOR)
+		current->maj_flt++;
+	else
+		current->min_flt++;
 	return;
 
 	/* Something tried to access memory that isn't in our memory map.

arch/arm/mm/fault.c

@@ -183,20 +183,20 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
 	 */
 survive:
 	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, fsr & (1 << 11));
-
-	/*
-	 * Handle the "normal" cases first - successful and sigbus
-	 */
-	switch (fault) {
-	case VM_FAULT_MAJOR:
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
+			goto out_of_memory;
+		else if (fault & VM_FAULT_SIGBUS)
+			return fault;
+		BUG();
+	}
+	if (fault & VM_FAULT_MAJOR)
 		tsk->maj_flt++;
-		return fault;
-	case VM_FAULT_MINOR:
+	else
 		tsk->min_flt++;
-	case VM_FAULT_SIGBUS:
-		return fault;
-	}
+	return fault;
 
+out_of_memory:
 	if (!is_init(tsk))
 		goto out;
 
@@ -249,7 +249,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	/*
 	 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
 	 */
-	if (fault >= VM_FAULT_MINOR)
+	if (likely(!(fault & VM_FAULT_ERROR)))
 		return 0;
 
 	/*
@@ -259,8 +259,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (!user_mode(regs))
 		goto no_context;
 
-	switch (fault) {
-	case VM_FAULT_OOM:
+	if (fault & VM_FAULT_OOM) {
 		/*
 		 * We ran out of memory, or some other thing
 		 * happened to us that made us unable to handle
@@ -269,25 +268,22 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		printk("VM: killing process %s\n", tsk->comm);
 		do_exit(SIGKILL);
 		return 0;
-
-	case VM_FAULT_SIGBUS:
+	}
+	if (fault & VM_FAULT_SIGBUS) {
 		/*
 		 * We had some memory, but were unable to
 		 * successfully fix up this page fault.
 		 */
 		sig = SIGBUS;
 		code = BUS_ADRERR;
-		break;
-
-	default:
+	} else {
 		/*
 		 * Something tried to access memory that
 		 * isn't in our memory map..
 		 */
 		sig = SIGSEGV;
 		code = fault == VM_FAULT_BADACCESS ?
 			SEGV_ACCERR : SEGV_MAPERR;
-		break;
 	}
 
 	__do_user_fault(tsk, addr, fsr, sig, code, regs);

arch/arm26/mm/fault.c

@@ -170,20 +170,20 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
 	 */
 survive:
 	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(fsr));
-
-	/*
-	 * Handle the "normal" cases first - successful and sigbus
-	 */
-	switch (fault) {
-	case VM_FAULT_MAJOR:
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
+			goto out_of_memory;
+		else if (fault & VM_FAULT_SIGBUS)
+			return fault;
+		BUG();
+	}
+	if (fault & VM_FAULT_MAJOR)
 		tsk->maj_flt++;
-		return fault;
-	case VM_FAULT_MINOR:
+	else
 		tsk->min_flt++;
-	case VM_FAULT_SIGBUS:
-		return fault;
-	}
+	return fault;
 
+out_of_memory:
 	fault = -3; /* out of memory */
 	if (!is_init(tsk))
 		goto out;
@@ -225,13 +225,11 @@ int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	/*
 	 * Handle the "normal" case first
 	 */
-	switch (fault) {
-	case VM_FAULT_MINOR:
-	case VM_FAULT_MAJOR:
+	if (likely(!(fault & VM_FAULT_ERROR)))
 		return 0;
-	case VM_FAULT_SIGBUS:
+	if (fault & VM_FAULT_SIGBUS)
 		goto do_sigbus;
-	}
+	/* else VM_FAULT_OOM */
 
 	/*
 	 * If we are in kernel mode at this point, we

arch/avr32/mm/fault.c

@@ -64,6 +64,7 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 	int writeaccess;
 	long signr;
 	int code;
+	int fault;
 
 	if (notify_page_fault(regs, ecr))
 		return;
@@ -132,20 +133,18 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 	 * fault.
 	 */
 survive:
-	switch (handle_mm_fault(mm, vma, address, writeaccess)) {
-	case VM_FAULT_MINOR:
-		tsk->min_flt++;
-		break;
-	case VM_FAULT_MAJOR:
-		tsk->maj_flt++;
-		break;
-	case VM_FAULT_SIGBUS:
-		goto do_sigbus;
-	case VM_FAULT_OOM:
-		goto out_of_memory;
-	default:
+	fault = handle_mm_fault(mm, vma, address, writeaccess);
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
+			goto out_of_memory;
+		else if (fault & VM_FAULT_SIGBUS)
+			goto do_sigbus;
 		BUG();
 	}
+	if (fault & VM_FAULT_MAJOR)
+		tsk->maj_flt++;
+	else
+		tsk->min_flt++;
 
 	up_read(&mm->mmap_sem);
 	return;

arch/cris/mm/fault.c

@@ -179,6 +179,7 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
 	siginfo_t info;
+	int fault;
 
         D(printk("Page fault for %lX on %X at %lX, prot %d write %d\n",
                  address, smp_processor_id(), instruction_pointer(regs),
@@ -283,18 +284,18 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
 	 * the fault.
 	 */
 
-	switch (handle_mm_fault(mm, vma, address, writeaccess & 1)) {
-	case VM_FAULT_MINOR:
-		tsk->min_flt++;
-		break;
-	case VM_FAULT_MAJOR:
-		tsk->maj_flt++;
-		break;
-	case VM_FAULT_SIGBUS:
-		goto do_sigbus;
-	default:
-		goto out_of_memory;
+	fault = handle_mm_fault(mm, vma, address, writeaccess & 1);
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
+			goto out_of_memory;
+		else if (fault & VM_FAULT_SIGBUS)
+			goto do_sigbus;
+		BUG();
 	}
+	if (fault & VM_FAULT_MAJOR)
+		tsk->maj_flt++;
+	else
+		tsk->min_flt++;
 
 	up_read(&mm->mmap_sem);
 	return;

arch/frv/mm/fault.c

@@ -40,6 +40,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 	pud_t *pue;
 	pte_t *pte;
 	int write;
+	int fault;
 
 #if 0
 	const char *atxc[16] = {
@@ -162,18 +163,18 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	switch (handle_mm_fault(mm, vma, ear0, write)) {
-	case VM_FAULT_MINOR:
-		current->min_flt++;
-		break;
-	case VM_FAULT_MAJOR:
-		current->maj_flt++;
-		break;
-	case VM_FAULT_SIGBUS:
-		goto do_sigbus;
-	default:
-		goto out_of_memory;
+	fault = handle_mm_fault(mm, vma, ear0, write);
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
+			goto out_of_memory;
+		else if (fault & VM_FAULT_SIGBUS)
+			goto do_sigbus;
+		BUG();
 	}
+	if (fault & VM_FAULT_MAJOR)
+		current->maj_flt++;
+	else
+		current->min_flt++;
 
 	up_read(&mm->mmap_sem);
 	return;

arch/i386/mm/fault.c

@@ -303,6 +303,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
 	struct vm_area_struct * vma;
 	unsigned long address;
 	int write, si_code;
+	int fault;
 
 	/* get the address */
         address = read_cr2();
@@ -422,20 +423,18 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs,
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	switch (handle_mm_fault(mm, vma, address, write)) {
-		case VM_FAULT_MINOR:
-			tsk->min_flt++;
-			break;
-		case VM_FAULT_MAJOR:
-			tsk->maj_flt++;
-			break;
-		case VM_FAULT_SIGBUS:
-			goto do_sigbus;
-		case VM_FAULT_OOM:
+	fault = handle_mm_fault(mm, vma, address, write);
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
-		default:
-			BUG();
+		else if (fault & VM_FAULT_SIGBUS)
+			goto do_sigbus;
+		BUG();
 	}
+	if (fault & VM_FAULT_MAJOR)
+		tsk->maj_flt++;
+	else
+		tsk->min_flt++;
 
 	/*
 	 * Did it hit the DOS screen memory VA from vm86 mode?

arch/ia64/mm/fault.c

@@ -80,6 +80,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
 	struct mm_struct *mm = current->mm;
 	struct siginfo si;
 	unsigned long mask;
+	int fault;
 
 	/* mmap_sem is performance critical.... */
 	prefetchw(&mm->mmap_sem);
@@ -147,26 +148,25 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
 	 * sure we exit gracefully rather than endlessly redo the
 	 * fault.
 	 */
-	switch (handle_mm_fault(mm, vma, address, (mask & VM_WRITE) != 0)) {
-	      case VM_FAULT_MINOR:
-		++current->min_flt;
-		break;
-	      case VM_FAULT_MAJOR:
-		++current->maj_flt;
-		break;
-	      case VM_FAULT_SIGBUS:
+	fault = handle_mm_fault(mm, vma, address, (mask & VM_WRITE) != 0);
+	if (unlikely(fault & VM_FAULT_ERROR)) {
 		/*
 		 * We ran out of memory, or some other thing happened
 		 * to us that made us unable to handle the page fault
 		 * gracefully.
 		 */
-		signal = SIGBUS;
-		goto bad_area;
-	      case VM_FAULT_OOM:
-		goto out_of_memory;
-	      default:
+		if (fault & VM_FAULT_OOM) {
+			goto out_of_memory;
+		} else if (fault & VM_FAULT_SIGBUS) {
+			signal = SIGBUS;
+			goto bad_area;
+		}
 		BUG();
 	}
+	if (fault & VM_FAULT_MAJOR)
+		current->maj_flt++;
+	else
+		current->min_flt++;
 	up_read(&mm->mmap_sem);
 	return;
 

arch/m32r/mm/fault.c

@@ -80,6 +80,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
 	struct vm_area_struct * vma;
 	unsigned long page, addr;
 	int write;
+	int fault;
 	siginfo_t info;
 
 	/*
@@ -195,20 +196,18 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code,
 	 */
 	addr = (address & PAGE_MASK);
 	set_thread_fault_code(error_code);
-	switch (handle_mm_fault(mm, vma, addr, write)) {
-		case VM_FAULT_MINOR:
-			tsk->min_flt++;
-			break;
-		case VM_FAULT_MAJOR:
-			tsk->maj_flt++;
-			break;
-		case VM_FAULT_SIGBUS:
-			goto do_sigbus;
-		case VM_FAULT_OOM:
+	fault = handle_mm_fault(mm, vma, addr, write);
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
-		default:
-			BUG();
+		else if (fault & VM_FAULT_SIGBUS)
+			goto do_sigbus;
+		BUG();
 	}
+	if (fault & VM_FAULT_MAJOR)
+		tsk->maj_flt++;
+	else
+		tsk->min_flt++;
 	set_thread_fault_code(0);
 	up_read(&mm->mmap_sem);
 	return;