[PATCH 02/25] mm: Introduce mm_fault_accounting()

[Peter Xu <peterx@redhat.com>]

Provide this helper for doing memory page fault accounting across archs.  It
can be defined unconditionally because perf_sw_event() is always defined, and
perf_sw_event() will be a no-op if !CONFIG_PERF_EVENTS.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/linux/mm.h |  2 ++
 mm/memory.c        | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f3fe7371855c..b96db64125be 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1649,6 +1649,8 @@ void truncate_pagecache_range(struct inode *inode, loff_t offset, loff_t end);
 int truncate_inode_page(struct address_space *mapping, struct page *page);
 int generic_error_remove_page(struct address_space *mapping, struct page *page);
 int invalidate_inode_page(struct page *page);
+void mm_fault_accounting(struct task_struct *task, struct pt_regs *regs,
+			 unsigned long address, bool major);
 
 #ifdef CONFIG_MMU
 extern vm_fault_t handle_mm_fault(struct vm_area_struct *vma,
diff --git a/mm/memory.c b/mm/memory.c
index f703fe8c8346..c4f8319f0ed8 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -71,6 +71,8 @@
 #include <linux/dax.h>
 #include <linux/oom.h>
 #include <linux/numa.h>
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
 
 #include <trace/events/kmem.h>
 
@@ -4397,6 +4399,22 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
 }
 EXPORT_SYMBOL_GPL(handle_mm_fault);
 
+void mm_fault_accounting(struct task_struct *task, struct pt_regs *regs,
+			 unsigned long address, bool major)
+{
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+	if (major) {
+		task->maj_flt++;
+		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+			      regs, address);
+	} else {
+		task->min_flt++;
+		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+			      regs, address);
+	}
+}
+EXPORT_SYMBOL_GPL(mm_fault_accounting);
+
 #ifndef __PAGETABLE_P4D_FOLDED
 /*
  * Allocate p4d page table.
-- 
2.26.2