parisc/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 parisc.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 18162ce4261ef63eae30818c2eb5ffa4608ba728..f247a3480e8e0cd7e276f4fd04004cbb608b3e11 100644 (file)
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -175,10 +175,12 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
        struct mm_struct *mm = tsk->mm;
        unsigned long acc_type;
        int fault;
+       unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
        if (in_atomic() || !mm)
                goto no_context;
 
+retry:
        down_read(&mm->mmap_sem);
        vma = find_vma_prev(mm, address, &prev_vma);
        if (!vma || address < vma->vm_start)
@@ -201,7 +203,12 @@ good_area:
         * fault.
         */
 
-       fault = handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0);
+       fault = handle_mm_fault(mm, vma, address,
+                       flags | ((acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0));
+
+       if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+               return;
+
        if (unlikely(fault & VM_FAULT_ERROR)) {
                /*
                 * We hit a shared mapping outside of the file, or some
@@ -214,10 +221,23 @@ good_area:
                        goto bad_area;
                BUG();
        }
-       if (fault & VM_FAULT_MAJOR)
-               current->maj_flt++;
-       else
-               current->min_flt++;
+       if (flags & FAULT_FLAG_ALLOW_RETRY) {
+               if (fault & VM_FAULT_MAJOR)
+                       current->maj_flt++;
+               else
+                       current->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;