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Subject[PATCH 20/20] sparc/mm/fault_64.c: Port OOM changes to do_sparc64_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 64-bit sparc.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
arch/sparc/mm/fault_64.c | 38 +++++++++++++++++++++++++++++++-------
1 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 504c062..899585b 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -279,6 +279,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
unsigned int insn = 0;
int si_code, fault_code, fault;
unsigned long address, mm_rss;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

fault_code = get_thread_fault_code();

@@ -333,6 +334,8 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
insn = get_fault_insn(regs, insn);
goto handle_kernel_fault;
}
+
+retry:
down_read(&mm->mmap_sem);
}

@@ -423,7 +426,12 @@ good_area:
goto bad_area;
}

- fault = handle_mm_fault(mm, vma, address, (fault_code & FAULT_CODE_WRITE) ? FAULT_FLAG_WRITE : 0);
+ fault = handle_mm_fault(mm, vma, address,
+ flags | ((fault_code & FAULT_CODE_WRITE) ? FAULT_FLAG_WRITE : 0);
+
+ 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;
@@ -431,12 +439,28 @@ good_area:
goto do_sigbus;
BUG();
}
- if (fault & VM_FAULT_MAJOR) {
- current->maj_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
- } else {
- current->min_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
+
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR) {
+ current->maj_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
+ 1, regs, address);
+ } else {
+ current->min_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
+ 1, regs, address);
+ }
+ 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);

--
1.7.5.4


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