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

arch/s390/mm/fault.c

+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.