[PATCH v5 11/25] mm/mips: Use general page fault accounting

From: Peter Xu
Date: Tue Jul 07 2020 - 18:50:48 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: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
CC: linux-mips@xxxxxxxxxxxxxxx
Acked-by: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
arch/mips/mm/fault.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index b1db39784db9..7c871b14e74a 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -96,6 +96,8 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,

if (user_mode(regs))
flags |= FAULT_FLAG_USER;
+
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
retry:
mmap_read_lock(mm);
vma = find_vma(mm, address);
@@ -152,12 +154,11 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags, NULL);
+ fault = handle_mm_fault(vma, address, flags, regs);

if (fault_signal_pending(fault, regs))
return;

- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
@@ -168,15 +169,6 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
- if (fault & VM_FAULT_MAJOR) {
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
- regs, address);
- tsk->maj_flt++;
- } else {
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
- regs, address);
- tsk->min_flt++;
- }
if (fault & VM_FAULT_RETRY) {
flags |= FAULT_FLAG_TRIED;

--
2.26.2