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Subject[PATCH 01/19 v2] avr32/mm/fault.c: Port OOM changes to do_page_fault
Date
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 AVR32.

Signed-off-by: Mohd. Faris <mohdfarisq2010@gmail.com>
Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
arch/avr32/mm/fault.c | 30 +++++++++++++++++++++++++-----
1 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index f7040a1..0362d03 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -65,6 +65,7 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
long signr;
int code;
int fault;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

if (notify_page_fault(regs, ecr))
return;
@@ -86,6 +87,7 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)

local_irq_enable();

+retry:
down_read(&mm->mmap_sem);

vma = find_vma(mm, address);
@@ -122,6 +124,7 @@ good_area:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
writeaccess = 1;
+ flags |= FAULT_FLAG_WRITE;
break;
default:
panic("Unhandled case %lu in do_page_fault!", ecr);
@@ -132,7 +135,11 @@ good_area:
* sure we exit gracefully rather than endlessly redo the
* fault.
*/
- fault = handle_mm_fault(mm, vma, address, writeaccess ? 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;
@@ -140,10 +147,23 @@ good_area:
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;
--
1.7.5.4


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