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Subject[PATCH 12/20] frv/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 frv.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
arch/frv/mm/fault.c | 30 +++++++++++++++++++++++++-----
1 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c
index a325d57..478e405 100644
--- a/arch/frv/mm/fault.c
+++ b/arch/frv/mm/fault.c
@@ -41,6 +41,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
pte_t *pte;
int write;
int fault;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

#if 0
const char *atxc[16] = {
@@ -82,6 +83,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
if (in_atomic() || !mm)
goto no_context;

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

vma = find_vma(mm, ear0);
@@ -142,6 +144,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
write = 1;
+ flags |= FAULT_FLAG_WRITE;
break;

/* handle read from protected page */
@@ -163,7 +166,11 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(mm, vma, ear0, write ? FAULT_FLAG_WRITE : 0);
+ fault = handle_mm_fault(mm, vma, ear0, 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;
@@ -171,10 +178,23 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
goto do_sigbus;
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;
--
1.7.5.4


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