linux-kernel - [PATCH 10/26] mm/microblaze: Use general page fault accounting

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Date:   Fri, 19 Jun 2020 12:05:22 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     Gerald Schaefer <gerald.schaefer@...ibm.com>, peterx@...hat.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Will Deacon <will@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Michal Simek <monstr@...str.eu>
Subject: [PATCH 10/26] mm/microblaze: 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.

Add the missing PERF_COUNT_SW_PAGE_FAULTS perf events too.  Note, the other two
perf events (PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN]) were done in handle_mm_fault().

CC: Michal Simek <monstr@...str.eu>
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/microblaze/mm/fault.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index 9abfa5224386..3d58dbd227cd 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -28,6 +28,7 @@
 #include <linux/mman.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>
+#include <linux/perf_event.h>
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -122,6 +123,8 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
 	if (user_mode(regs))
 		flags |= FAULT_FLAG_USER;
 
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+
 	/* When running in the kernel we expect faults to occur only to
 	 * addresses in user space.  All other faults represent errors in the
 	 * kernel and should generate an OOPS.  Unfortunately, in the case of an
@@ -215,7 +218,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
 	 * 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;
@@ -231,10 +234,6 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
 	}
 
 	if (flags & FAULT_FLAG_ALLOW_RETRY) {
-		if (unlikely(fault & VM_FAULT_MAJOR))
-			current->maj_flt++;
-		else
-			current->min_flt++;
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
-- 
2.26.2