mm/arc: use general page fault accounting

Use the general page fault accounting by passing regs into
handle_mm_fault().  It naturally solve the issue of multiple page fault
accounting when page fault retry happened.

Fix PERF_COUNT_SW_PAGE_FAULTS perf event manually for page fault retries,
by moving it before taking mmap_sem.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Link: http://lkml.kernel.org/r/20200707225021.200906-4-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 587dea5..f5657cb 100644 (file)
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -105,6 +105,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
        if (write)
                flags |= FAULT_FLAG_WRITE;
 
+       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 retry:
        mmap_read_lock(mm);
 
@@ -130,7 +131,7 @@ retry:
                goto bad_area;
        }
 
-       fault = handle_mm_fault(vma, address, flags, NULL);
+       fault = handle_mm_fault(vma, address, flags, regs);
 
        /* Quick path to respond to signals */
        if (fault_signal_pending(fault, regs)) {
@@ -155,22 +156,9 @@ bad_area:
         * Major/minor page fault accounting
         * (in case of retry we only land here once)
         */
-       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
-
-       if (likely(!(fault & VM_FAULT_ERROR))) {
-               if (fault & VM_FAULT_MAJOR) {
-                       tsk->maj_flt++;
-                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
-                                     regs, address);
-               } else {
-                       tsk->min_flt++;
-                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
-                                     regs, address);
-               }
-
+       if (likely(!(fault & VM_FAULT_ERROR)))
                /* Normal return path: fault Handled Gracefully */
                return;
-       }
 
        if (!user_mode(regs))
                goto no_context;