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From:   Peter Xu <peterx@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     Gerald Schaefer <gerald.schaefer@de.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>, peterx@redhat.com,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Nick Hu <nickhu@andestech.com>,
        Greentime Hu <green.hu@gmail.com>,
        Vincent Chen <deanbo422@gmail.com>
Subject: [PATCH 13/25] mm/nds32: Use mm_fault_accounting()
Date:   Mon, 15 Jun 2020 18:15:55 -0400
Message-Id: <20200615221607.7764-14-peterx@redhat.com>
In-Reply-To: <20200615221607.7764-1-peterx@redhat.com>
References: <20200615221607.7764-1-peterx@redhat.com>
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Use the new mm_fault_accounting() helper for page fault accounting.

Avoid doing page fault accounting multiple times if the page fault is retried.
Since at it, move the accounting after releasing 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 f331e533edc2..11537c03ab1d 100644
--- a/arch/nds32/mm/fault.c
+++ b/arch/nds32/mm/fault.c
@@ -78,7 +78,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
 	int si_code;
-	vm_fault_t fault;
+	vm_fault_t fault, major = 0;
 	unsigned int mask = VM_ACCESS_FLAGS;
 	unsigned int flags = FAULT_FLAG_DEFAULT;
 
@@ -208,6 +208,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
 	 */
 
 	fault = handle_mm_fault(vma, addr, flags);
+	major |= fault & VM_FAULT_MAJOR;
 
 	/*
 	 * If we need to retry but a fatal signal is pending, handle the
@@ -229,22 +230,7 @@ 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;
 
@@ -257,6 +243,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
 	}
 
 	up_read(&mm->mmap_sem);
+	mm_fault_accounting(tsk, regs, addr, major);
 	return;
 
 	/*
-- 
2.26.2