linux-kernel - [PATCH 10/25] mm/m68k: Use mm_fault

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Date:   Mon, 15 Jun 2020 18:15:52 -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>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org
Subject: [PATCH 10/25] mm/m68k: 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.
Also, the perf events for page faults will be accounted too when the config has
CONFIG_PERF_EVENTS defined.  Do the accounting without mmap_sem.

CC: Geert Uytterhoeven <geert@...ux-m68k.org>
CC: linux-m68k@...ts.linux-m68k.org
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/m68k/mm/fault.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index 3bfb5c8ac3c7..6c6d6d77a1be 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -70,7 +70,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct * vma;
-	vm_fault_t fault;
+	vm_fault_t fault, major = 0;
 	unsigned int flags = FAULT_FLAG_DEFAULT;
 
 	pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
@@ -136,6 +136,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	 */
 
 	fault = handle_mm_fault(vma, address, flags);
+	major |= fault & VM_FAULT_MAJOR;
 	pr_debug("handle_mm_fault returns %x\n", fault);
 
 	if (fault_signal_pending(fault, regs))
@@ -151,16 +152,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 		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)
-			current->maj_flt++;
-		else
-			current->min_flt++;
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 
@@ -175,6 +167,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	}
 
 	up_read(&mm->mmap_sem);
+	mm_fault_accounting(current, regs, address, major);
 	return 0;
 
 /*
-- 
2.26.2