cris/mm/fault.c: Port OOM changes to do_page_fault

Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99
(mm: retry page fault when blocking on disk transfer) and
commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb
(x86,mm: make pagefault killable)

The above commits introduced changes into the x86 pagefault handler
for making the page fault handler retryable as well as killable.

These changes reduce the mmap_sem hold time, which is crucial
during OOM killer invocation.

Port these changes to CRIS.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>

1 files changed, 26 insertions, 5 deletions

diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index b4760d86e1bb..45fd542cf173 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -58,6 +58,8 @@ 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);
 
         D(printk(KERN_DEBUG
                  "Page fault for %lX on %X at %lX, prot %d write %d\n",
@@ -115,6 +117,7 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
         if (in_atomic() || !mm)
                 goto no_context;
 
+retry:
         down_read(&mm->mmap_sem);
         vma = find_vma(mm, address);
         if (!vma)
@@ -163,7 +166,11 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
          * the fault.
          */
 
-        fault = handle_mm_fault(mm, vma, address, (writeaccess & 1) ? 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;
@@ -171,10 +178,24 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
                         goto do_sigbus;
                 BUG();
         }
-        if (fault & VM_FAULT_MAJOR)
-                tsk->maj_flt++;
-        else
-                tsk->min_flt++;
+
+        if (flags & FAULT_FLAG_ALLOW_RETRY) {
+                if (fault & VM_FAULT_MAJOR)
+                        tsk->maj_flt++;
+                else
+                        tsk->min_flt++;
+                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;
+                }
+        }
 
         up_read(&mm->mmap_sem);
         return;