linux-kernel - [PATCH 19/25] mm/s390: Use mm_fault

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Message-Id: <20200615222302.8452-1-peterx@redhat.com>
Date:   Mon, 15 Jun 2020 18:23:02 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Xu <peterx@...hat.com>,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        linux-s390@...r.kernel.org
Subject: [PATCH 19/25] mm/s390: Use mm_fault_accounting()

Use the new mm_fault_accounting() helper for page fault accounting.

Avoid doing page fault accounting multiple times if the page fault is retried.

CC: Heiko Carstens <heiko.carstens@...ibm.com>
CC: Vasily Gorbik <gor@...ux.ibm.com>
CC: Christian Borntraeger <borntraeger@...ibm.com>
CC: linux-s390@...r.kernel.org
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/s390/mm/fault.c | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index dedc28be27ab..8ca207635b59 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -392,7 +392,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
 	unsigned long trans_exc_code;
 	unsigned long address;
 	unsigned int flags;
-	vm_fault_t fault;
+	vm_fault_t fault, major = 0;
 
 	tsk = current;
 	/*
@@ -428,7 +428,6 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
 	}
 
 	address = trans_exc_code & __FAIL_ADDR_MASK;
-	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 	flags = FAULT_FLAG_DEFAULT;
 	if (user_mode(regs))
 		flags |= FAULT_FLAG_USER;
@@ -480,6 +479,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
 	 * the fault.
 	 */
 	fault = handle_mm_fault(vma, address, flags);
+	major |= fault & VM_FAULT_MAJOR;
 	if (fault_signal_pending(fault, regs)) {
 		fault = VM_FAULT_SIGNAL;
 		if (flags & FAULT_FLAG_RETRY_NOWAIT)
@@ -489,21 +489,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
 	if (unlikely(fault & VM_FAULT_ERROR))
 		goto out_up;
 
-	/*
-	 * 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.
-	 */
 	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, address);
-		} else {
-			tsk->min_flt++;
-			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
-				      regs, address);
-		}
 		if (fault & VM_FAULT_RETRY) {
 			if (IS_ENABLED(CONFIG_PGSTE) && gmap &&
 			    (flags & FAULT_FLAG_RETRY_NOWAIT)) {
@@ -519,6 +505,9 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
 			goto retry;
 		}
 	}
+
+	mm_fault_accounting(tsk, regs, address, major);
+
 	if (IS_ENABLED(CONFIG_PGSTE) && gmap) {
 		address =  __gmap_link(gmap, current->thread.gmap_addr,
 				       address);
-- 
2.26.2