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authorHeiko Carstens <heiko.carstens@de.ibm.com>2011-05-26 09:48:30 +0200
committerHeiko Carstens <heiko.carstens@de.ibm.com>2011-05-26 09:48:25 +0200
commit33ce614029576b8585e271fd7d90746a37114a15 (patch)
tree04f6a764b0ed82f0d6d0647b64547ad24d19830b
parent99583181cbf2252dd0554eef6f419a6b22cd33ea (diff)
[S390] mm: add page fault retry handling
s390 arch backend for d065bd81 "mm: retry page fault when blocking on disk transfer". Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
-rw-r--r--arch/s390/mm/fault.c41
1 files changed, 28 insertions, 13 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index b57723aee848..fe103e891e7a 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -280,7 +280,8 @@ static inline int do_exception(struct pt_regs *regs, int access,
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned long address;
- int fault, write;
+ unsigned int flags;
+ int fault;
if (notify_page_fault(regs))
return 0;
@@ -299,6 +300,10 @@ static inline int do_exception(struct pt_regs *regs, int access,
address = trans_exc_code & __FAIL_ADDR_MASK;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
+ flags = FAULT_FLAG_ALLOW_RETRY;
+ if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
+ flags |= FAULT_FLAG_WRITE;
+retry:
down_read(&mm->mmap_sem);
fault = VM_FAULT_BADMAP;
@@ -328,21 +333,31 @@ static inline int do_exception(struct pt_regs *regs, int access,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- write = (access == VM_WRITE ||
- (trans_exc_code & store_indication) == 0x400) ?
- FAULT_FLAG_WRITE : 0;
- fault = handle_mm_fault(mm, vma, address, write);
+ fault = handle_mm_fault(mm, vma, address, flags);
if (unlikely(fault & VM_FAULT_ERROR))
goto out_up;
- if (fault & VM_FAULT_MAJOR) {
- tsk->maj_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
- regs, address);
- } else {
- tsk->min_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
- regs, address);
+ /*
+ * Major/minor page fault accounting is only done on the
+ * initial attempt. If we go through a retry, it is extremely
+ * likely that the page will be found in page cache at that point.
+ */
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR) {
+ tsk->maj_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
+ regs, address);
+ } else {
+ tsk->min_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
+ regs, address);
+ }
+ if (fault & VM_FAULT_RETRY) {
+ /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+ * of starvation. */
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ goto retry;
+ }
}
/*
* The instruction that caused the program check will