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Commit 33ce6140 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

[S390] mm: add page fault retry handling



s390 arch backend for d065bd81 "mm: retry page fault when blocking on
disk transfer".

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent 99583181
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+28 −13
Original line number Diff line number Diff line
@@ -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;
@@ -328,13 +333,16 @@ 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;

	/*
	 * 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,
@@ -344,6 +352,13 @@ static inline int do_exception(struct pt_regs *regs, int access,
			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
	 * be repeated. Don't signal single step via SIGTRAP.