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m68k/mm: Port OOM changes to do_page_fault() 

Commit d065bd810b
(mm: retry page fault when blocking on disk transfer) and
commit 37b23e0525
(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 <consul.kautuk@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
This commit is contained in:
Kautuk Consul 2012-03-25 06:37:48 -04:00 committed by Geert Uytterhoeven
parent 107b5d5302
commit b637a6b167
1 changed files with 34 additions and 8 deletions
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34
arch/m68k/mm/fault.c
View File

@ -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 @@ good_area:
#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 @@ 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 0;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
@ -150,10 +155,31 @@ good_area:
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;