m68k/mm/fault.c: Port OOM changes to do_page_fault

PATCH Superseded Kautuk Consul 1 participant 2 messages Mar 20, 2012 m68k architecture

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Kautuk Consul

author

2012-03-20 13:22 UTC #0 lore raw

PATCH 8/20 m68k/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 m68k.

Signed-off-by Kautuk Consul <[email protected]>

---
 arch/m68k/mm/fault.c |   31 ++++++++++++++++++++++++++-----
 1 files changed, 26 insertions(+), 5 deletions(-)

arch/m68k/mm/fault.c +26 -5

index 2db6099..27879bd 100644
@@ -74,6 +74,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct * vma;
 	int write, fault;
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 #ifdef DEBUG
 	printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",

@@ -88,6 +89,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+retry:
 	down_read(&mm->mmap_sem);
 
 	vma = find_vma(mm, address);

@@ -126,6 +128,7 @@ good_area:
 			if (!(vma->vm_flags & VM_WRITE))
 				goto acc_err;
 			write++;
+			flags |= FAULT_FLAG_WRITE;
 			break;
 		case 1:		/* read, present */
 			goto acc_err;

@@ -140,10 +143,14 @@ good_area:
 	 * the fault.
 	 */
 
-	fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
+	fault = handle_mm_fault(mm, vma, address, flags);
 #ifdef DEBUG
 	printk("handle_mm_fault returns %d\n",fault);
 #endif
+
+	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;

@@ -151,10 +158,24 @@ good_area:
 			goto bus_err;
 		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 0;

Signature · 1 line

1.7.5.4

Kautuk Consul

author

2012-03-20 16:04 UTC #1 lore raw

Hi,

Im sorry there is a defect in this patch.

I am now posting a v2 of this patch.

Quoted 48 lines · Kautuk Consul

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 m68k.

Signed-off-by Kautuk Consul <[email protected]>

---
arch/m68k/mm/fault.c | 31 ++++++++++++++++++++++++++-----

 1 files changed, 26 insertions(+), 5 deletions(-)

arch/m68k/mm/fault.c +3 -0

index 2db6099..27879bd 100644
@@ -74,6 +74,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
        struct mm_struct *mm = current->mm;
        struct vm_area_struct * vma;
        int write, fault;
+       unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
  #ifdef DEBUG
        printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",

@@ -88,6 +89,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
        if (in_atomic() || !mm)
                goto no_context;
 
+retry:
        down_read(&mm->mmap_sem);
 
        vma = find_vma(mm, address);

@@ -126,6 +128,7 @@ good_area:
                        if (!(vma->vm_flags & VM_WRITE))
                                goto acc_err;
                        write++;
+                       flags |= FAULT_FLAG_WRITE;
                        break;

case 1: /* read, present */ goto acc_err;

arch/m68k/mm/fault.c +0 -0

@@ -140,10 +143,14 @@ good_area:
         * the fault.

arch/m68k/mm/fault.c good_area: · line 152

Quoted 10 lines

arch/m68k/mm/fault.c +4 -1

         */
 
-       fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
+       fault = handle_mm_fault(mm, vma, address, flags);
  #ifdef DEBUG
        printk("handle_mm_fault returns %d\n",fault);
  #endif
+
+       if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+               return;

Incorrect. This function returns an int.

Quoted 36 lines

arch/m68k/mm/fault.c +19 -5

+
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;

@@ -151,10 +158,24 @@ good_area:
                        goto bus_err;
                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 0;
--

1.7.5.4