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* [PATCH v5 03/25] mm/arc: Use general page fault accounting
       [not found] <20200707225021.200906-1-peterx@redhat.com>
@ 2020-07-07 22:49 ` Peter Xu
  0 siblings, 0 replies; only message in thread
From: Peter Xu @ 2020-07-07 22:49 UTC (permalink / raw)
  To: linux-kernel, linux-mm
  Cc: Andrea Arcangeli, John Hubbard, Linus Torvalds, peterx,
	Vineet Gupta, Michael Ellerman, David Rientjes, Andrew Morton,
	linux-snps-arc, Will Deacon, Gerald Schaefer

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.

Fix PERF_COUNT_SW_PAGE_FAULTS perf event manually for page fault retries, by
moving it before taking mmap_sem.

CC: Vineet Gupta <vgupta@synopsys.com>
CC: linux-snps-arc@lists.infradead.org
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 arch/arc/mm/fault.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 587dea524e6b..f5657cb68e4f 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -105,6 +105,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 	if (write)
 		flags |= FAULT_FLAG_WRITE;
 
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 retry:
 	mmap_read_lock(mm);
 
@@ -130,7 +131,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 		goto bad_area;
 	}
 
-	fault = handle_mm_fault(vma, address, flags, NULL);
+	fault = handle_mm_fault(vma, address, flags, regs);
 
 	/* Quick path to respond to signals */
 	if (fault_signal_pending(fault, regs)) {
@@ -155,22 +156,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
 	 * Major/minor page fault accounting
 	 * (in case of retry we only land here once)
 	 */
-	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
-
-	if (likely(!(fault & VM_FAULT_ERROR))) {
-		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 (likely(!(fault & VM_FAULT_ERROR)))
 		/* Normal return path: fault Handled Gracefully */
 		return;
-	}
 
 	if (!user_mode(regs))
 		goto no_context;
-- 
2.26.2


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     [not found] <20200707225021.200906-1-peterx@redhat.com>
2020-07-07 22:49 ` [PATCH v5 03/25] mm/arc: Use general page fault accounting Peter Xu

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