cris/mm/fault.c: Port OOM changes to do_page_fault
Kautuk Consul [Tue, 20 Mar 2012 13:24:05 +0000 (14:24 +0100)]
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>

arch/cris/mm/fault.c

index b4760d8..45fd542 100644 (file)
@@ -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;