1 files changed, 84 insertions, 0 deletions
diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
new file mode 100644
index 000000000..c141ea9a9
--- /dev/null
+++ b/include/linux/page_counter.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_PAGE_COUNTER_H
+#define _LINUX_PAGE_COUNTER_H
+
+#include <linux/atomic.h>
+#include <linux/cache.h>
+#include <linux/kernel.h>
+#include <asm/page.h>
+
+struct page_counter {
+	/*
+	 * Make sure 'usage' does not share cacheline with any other field. The
+	 * memcg->memory.usage is a hot member of struct mem_cgroup.
+	 */
+	atomic_long_t usage;
+	CACHELINE_PADDING(_pad1_);
+
+	/* effective memory.min and memory.min usage tracking */
+	unsigned long emin;
+	atomic_long_t min_usage;
+	atomic_long_t children_min_usage;
+
+	/* effective memory.low and memory.low usage tracking */
+	unsigned long elow;
+	atomic_long_t low_usage;
+	atomic_long_t children_low_usage;
+
+	unsigned long watermark;
+	unsigned long failcnt;
+
+	/* Keep all the read most fields in a separete cacheline. */
+	CACHELINE_PADDING(_pad2_);
+
+	unsigned long min;
+	unsigned long low;
+	unsigned long high;
+	unsigned long max;
+	struct page_counter *parent;
+} ____cacheline_internodealigned_in_smp;
+
+#if BITS_PER_LONG == 32
+#define PAGE_COUNTER_MAX LONG_MAX
+#else
+#define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
+#endif
+
+static inline void page_counter_init(struct page_counter *counter,
+				     struct page_counter *parent)
+{
+	atomic_long_set(&counter->usage, 0);
+	counter->max = PAGE_COUNTER_MAX;
+	counter->parent = parent;
+}
+
+static inline unsigned long page_counter_read(struct page_counter *counter)
+{
+	return atomic_long_read(&counter->usage);
+}
+
+void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
+void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
+bool page_counter_try_charge(struct page_counter *counter,
+			     unsigned long nr_pages,
+			     struct page_counter **fail);
+void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
+void page_counter_set_min(struct page_counter *counter, unsigned long nr_pages);
+void page_counter_set_low(struct page_counter *counter, unsigned long nr_pages);
+
+static inline void page_counter_set_high(struct page_counter *counter,
+					 unsigned long nr_pages)
+{
+	WRITE_ONCE(counter->high, nr_pages);
+}
+
+int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
+int page_counter_memparse(const char *buf, const char *max,
+			  unsigned long *nr_pages);
+
+static inline void page_counter_reset_watermark(struct page_counter *counter)
+{
+	counter->watermark = page_counter_read(counter);
+}
+
+#endif /* _LINUX_PAGE_COUNTER_H */