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Commit b637a6b1 authored by Kautuk Consul's avatar Kautuk Consul Committed by Geert Uytterhoeven
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m68k/mm: Port OOM changes to do_page_fault() 



Commit d065bd81
(mm: retry page fault when blocking on disk transfer) and
commit 37b23e05
(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: default avatarKautuk Consul <consul.kautuk@gmail.com>
Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
parent 107b5d53

arch/m68k/mm/fault.c

+34 −8
Original line number Diff line number Diff line
@@ -72,7 +72,8 @@ 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;

	int 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",
@@ -87,6 +88,7 @@ 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);
@@ -117,14 +119,13 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, 
#ifdef DEBUG

	printk("do_page_fault: good_area\n");

#endif

	write = 0;

	switch (error_code & 3) {

		default:	/* 3: write, present */

			/* fall through */

		case 2:		/* write, not present */

			if (!(vma->vm_flags & VM_WRITE))

				goto acc_err;

			write++;

			flags |= FAULT_FLAG_WRITE;

			break;

		case 1:		/* read, present */

			goto acc_err;
@@ -139,10 +140,14 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, 
	 * 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 0;



	if (unlikely(fault & VM_FAULT_ERROR)) {

		if (fault & VM_FAULT_OOM)

			goto out_of_memory;
@@ -150,10 +155,31 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, 
			goto bus_err;

		BUG();

	}



	/*

	 * Major/minor page fault accounting is only done on the

	 * initial attempt. If we go through a retry, it is extremely

	 * likely that the page will be found in page cache at that point.

	 */

	if (flags & FAULT_FLAG_ALLOW_RETRY) {

		if (fault & VM_FAULT_MAJOR)

			current->maj_flt++;

		else

			current->min_flt++;

		if (fault & VM_FAULT_RETRY) {

			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk

			 * of starvation. */

			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;