sh64: Port OOM changes to do_page_fault

Reflect the sh32 OOM changes for the sh64 page fault handler, too.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/mm/tlbflush_64.c

@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2000, 2001  Paolo Alberelli
  * Copyright (C) 2003  Richard Curnow (/proc/tlb, bug fixes)
- * Copyright (C) 2003 - 2009 Paul Mundt
+ * Copyright (C) 2003 - 2012 Paul Mundt
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
@@ -95,6 +95,8 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
 	const struct exception_table_entry *fixup;
+	unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+			      (writeaccess ? FAULT_FLAG_WRITE : 0));
 	pte_t *pte;
 	int fault;
 
@@ -124,6 +126,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+retry:
 	/* TLB misses upon some cache flushes get done under cli() */
 	down_read(&mm->mmap_sem);
 
@@ -188,7 +191,11 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
+	fault = handle_mm_fault(mm, vma, address, flags);
+
+	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+		return;
+
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
@@ -197,14 +204,27 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
 		BUG();
 	}
 
-	if (fault & VM_FAULT_MAJOR) {
-		tsk->maj_flt++;
-		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
-				     regs, address);
-	} else {
-		tsk->min_flt++;
-		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
-				     regs, address);
+	if (flags & FAULT_FLAG_ALLOW_RETRY) {
+		if (fault & VM_FAULT_MAJOR) {
+			tsk->maj_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+				      regs, address);
+		} else {
+			tsk->min_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+				      regs, address);
+		}
+
+		if (fault & VM_FAULT_RETRY) {
+			flags &= ~FAULT_FLAG_ALLOW_RETRY;
+
+			/*
+			 * No need to up_read(&mm->mmap_sem) as we would
+			 * have already released it in __lock_page_or_retry
+			 * in mm/filemap.c.
+			 */
+			goto retry;
+		}
 	}
 
 	/* If we get here, the page fault has been handled.  Do the TLB refill