[PATCH v4 03/26] mm/arc: Use general page fault accounting

From: Peter Xu
Date: Tue Jun 30 2020 - 16:45:29 EST


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.

CC: Vineet Gupta <vgupta@xxxxxxxxxxxx>
CC: linux-snps-arc@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
arch/arc/mm/fault.c | 18 +++---------------
1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 1b178dc147fd..5601dec319b5 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -106,6 +106,7 @@ 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);

@@ -131,7 +132,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
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)) {
@@ -156,22 +157,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
* 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;
--
2.26.2