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[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>
This commit is contained in:
Heiko Carstens 2011-05-26 09:48:30 +02:00
parent 99583181cb
commit 33ce614029
1 changed files with 28 additions and 13 deletions
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41
arch/s390/mm/fault.c
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@ -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