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Subject[PATCH 10/19 v2] hexagon/mm/vm_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 hexagon.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Acked-by: Richard Kuo <rkuo@codeaurora.org>
---
arch/hexagon/mm/vm_fault.c | 22 +++++++++++++++++-----
1 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
index c10b76f..06695cc 100644
--- a/arch/hexagon/mm/vm_fault.c
+++ b/arch/hexagon/mm/vm_fault.c
@@ -53,6 +53,8 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
int si_code = SEGV_MAPERR;
int fault;
const struct exception_table_entry *fixup;
+ unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ (cause > 0 ? FAULT_FLAG_WRITE : 0));

/*
* If we're in an interrupt or have no user context,
@@ -63,6 +65,7 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)

local_irq_enable();

+retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
@@ -96,14 +99,23 @@ good_area:
break;
}

- fault = handle_mm_fault(mm, vma, address, (cause > 0));
+ fault = handle_mm_fault(mm, vma, address, flags);
+
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return;

/* The most common case -- we are done. */
if (likely(!(fault & VM_FAULT_ERROR))) {
- 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;
+ goto retry;
+ }
+ }

up_read(&mm->mmap_sem);
return;
--
1.7.5.4


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