[PATCH 12/26] mm/nds32: Use general page fault accounting

Peter Xu
2020-06-19T16:07:43Z

retry happened.

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

CC: Nick Hu <nickhu@andestech.com>
CC: Greentime Hu <green.hu@gmail.com>
CC: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
arch/nds32/mm/fault.c | 19 +++----------------
1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/arch/nds32/mm/fault.c b/arch/nds32/mm/fault.c
index 22527129025c..e7344440623c 100644
--- a/arch/nds32/mm/fault.c
+++ b/arch/nds32/mm/fault.c
@@ -122,6 +122,8 @@ void do_page_fault(unsigned long entry, unsigned long addr,
if (unlikely(faulthandler_disabled() || !mm))
goto no_context;

+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
+
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
@@ -207,7 +209,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
* the fault.
*/

- fault = handle_mm_fault(vma, addr, flags, NULL);
+ fault = handle_mm_fault(vma, addr, flags, regs);

/*
* If we need to retry but a fatal signal is pending, handle the
@@ -229,22 +231,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
goto bad_area;
}

- /*
- * 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.
- */
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
if (flags & FAULT_FLAG_ALLOW_RETRY) {
- if (fault & VM_FAULT_MAJOR) {
- tsk->maj_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
- 1, regs, addr);
- } else {
- tsk->min_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
- 1, regs, addr);
- }
if (fault & VM_FAULT_RETRY) {
flags |= FAULT_FLAG_TRIED;

--
2.26.2