linux-kernel - [PATCH 18/25] mm/riscv: Use mm_fault

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Date:   Mon, 15 Jun 2020 18:16:00 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Gerald Schaefer <gerald.schaefer@...ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>, peterx@...hat.com,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv@...ts.infradead.org
Subject: [PATCH 18/25] mm/riscv: 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: Paul Walmsley <paul.walmsley@...ive.com>
CC: Palmer Dabbelt <palmer@...belt.com>
CC: Albert Ou <aou@...s.berkeley.edu>
CC: linux-riscv@...ts.infradead.org
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/riscv/mm/fault.c | 21 +++------------------
 1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index be84e32adc4c..9262338614d1 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -30,7 +30,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 	struct vm_area_struct *vma;
 	struct mm_struct *mm;
 	unsigned long addr, cause;
-	unsigned int flags = FAULT_FLAG_DEFAULT;
+	unsigned int flags = FAULT_FLAG_DEFAULT, major = 0;
 	int code = SEGV_MAPERR;
 	vm_fault_t fault;
 
@@ -65,9 +65,6 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 
 	if (user_mode(regs))
 		flags |= FAULT_FLAG_USER;
-
-	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
-
 retry:
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, addr);
@@ -111,6 +108,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 	 * the fault.
 	 */
 	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
@@ -128,21 +126,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 		BUG();
 	}
 
-	/*
-	 * 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, 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;
 
@@ -156,6 +140,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 	}
 
 	up_read(&mm->mmap_sem);
+	mm_fault_accounting(tsk, regs, addr, major);
 	return;
 
 	/*
-- 
2.26.2