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Subject[PATCH 07/20] microblaze/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 microblaze.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
arch/microblaze/mm/fault.c | 33 ++++++++++++++++++++++++++++-----
1 files changed, 28 insertions(+), 5 deletions(-)
diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index ae97d2c..60e19e6 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -93,6 +93,8 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
int code = SEGV_MAPERR;
int is_write = error_code & ESR_S;
int fault;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ (is_write ? FAULT_FLAG_WRITE : 0);

regs->ear = address;
regs->esr = error_code;
@@ -139,6 +141,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
if (kernel_mode(regs) && !search_exception_tables(regs->pc))
goto bad_area_nosemaphore;

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

@@ -211,7 +214,11 @@ good_area:
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(mm, vma, address, is_write ? 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;
@@ -219,11 +226,27 @@ good_area:
goto do_sigbus;
BUG();
}
- if (unlikely(fault & VM_FAULT_MAJOR))
- current->maj_flt++;
- else
- current->min_flt++;
+
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (unlikely(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);
+
/*
* keep track of tlb+htab misses that are good addrs but
* just need pte's created via handle_mm_fault()
--
1.7.5.4


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