ANDROID: mm: add GCMA sysfs stats

Add GCMA statistics for stored, loaded, evicted, cached and discarded
pages.

Bug: 236887352
Bug: 391879760
Change-Id: I7238ad6a0ab357402cda3f2357b1a731c50c597a
Signed-off-by: Minchan Kim <minchan@google.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

mm/Kconfig

@@ -998,6 +998,13 @@ config GCMA
 
 	  If unsure, say "n".
 
+config GCMA_SYSFS
+	bool "GCMA information through sysfs interface"
+	depends on GCMA && SYSFS
+	help
+	  This option exposes some sysfs attributes to get information
+	  from GCMA.
+
 config MEM_SOFT_DIRTY
 	bool "Track memory changes"
 	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS

mm/Makefile

@@ -120,6 +120,7 @@ obj-$(CONFIG_Z3FOLD)	+= z3fold.o
 obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
 obj-$(CONFIG_CMA)	+= cma.o
 obj-$(CONFIG_GCMA)	+= gcma.o
+obj-$(CONFIG_GCMA_SYSFS)	+= gcma_sysfs.o
 obj-$(CONFIG_NUMA) += numa.o
 obj-$(CONFIG_NUMA_MEMBLKS) += numa_memblks.o
 obj-$(CONFIG_NUMA_EMU) += numa_emulation.o

mm/gcma.c

@@ -13,6 +13,7 @@
 #include <linux/idr.h>
 #include <linux/slab.h>
 #include <linux/xarray.h>
+#include "gcma_sysfs.h"
 
 /*
  * page->page_type : area id
@@ -360,6 +361,7 @@ static struct page *gcma_alloc_page(void)
 		ClearPageGCMAFree(page);
 		set_page_count(page, 1);
 		spin_unlock(&area->free_pages_lock);
+		gcma_stat_inc(CACHED_PAGE);
 		break;
 	}
 
@@ -380,6 +382,7 @@ static void __gcma_free_page(struct page *page)
 static void gcma_free_page(struct page *page)
 {
 	__gcma_free_page(page);
+	gcma_stat_dec(CACHED_PAGE);
 }
 
 static inline void gcma_get_page(struct page *page)
@@ -473,6 +476,7 @@ static void isolate_gcma_page(struct gcma_inode *inode, struct page *page)
 	page_area_lock(page);
 	reset_gcma_page(page);
 	page_area_unlock(page);
+	gcma_stat_dec(CACHED_PAGE);
 }
 
 /*
@@ -584,6 +588,7 @@ again:
 		xa_unlock(&inode->pages);
 
 		isolate_gcma_page(inode, page);
+		gcma_stat_inc(DISCARDED_PAGE);
 		put_gcma_inode(inode);
 	}
 	local_irq_enable();
@@ -708,6 +713,8 @@ static void evict_gcma_lru_pages(unsigned long nr_request)
 		}
 		nr_evicted += isolated;
 	}
+
+	gcma_stat_add(EVICTED_PAGE, nr_evicted);
 }
 
 static void evict_gcma_pages(struct work_struct *work)
@@ -804,6 +811,7 @@ copy:
 	else
 		rotate_lru_page(g_page);
 
+	gcma_stat_inc(STORED_PAGE);
 out_unlock:
 	/*
 	 * If inode was just created but failed to add gcma page,
@@ -849,6 +857,7 @@ static int gcma_cc_load_page(int hash_id, struct cleancache_filekey key,
 	xa_unlock_irq(&inode->pages);
 
 	put_gcma_inode(inode);
+	gcma_stat_inc(LOADED_PAGE);
 
 	return 0;
 }

mm/gcma_sysfs.c

@@ -0,0 +1,92 @@
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include "gcma_sysfs.h"
+
+extern struct kobject *vendor_mm_kobj;
+static struct kobject gcma_kobj;
+
+static atomic64_t gcma_stats[NUM_OF_GCMA_STAT];
+
+void gcma_stat_inc(enum gcma_stat_type type)
+{
+	atomic64_inc(&gcma_stats[type]);
+}
+
+void gcma_stat_dec(enum gcma_stat_type type)
+{
+	atomic64_dec(&gcma_stats[type]);
+}
+
+void gcma_stat_add(enum gcma_stat_type type, unsigned long delta)
+{
+	atomic64_add(delta, &gcma_stats[type]);
+}
+
+/*
+ * This all compiles without CONFIG_SYSFS, but is a waste of space.
+ */
+
+#define GCMA_ATTR_RO(_name) \
+	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+
+static ssize_t stored_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&gcma_stats[STORED_PAGE]));
+}
+GCMA_ATTR_RO(stored);
+
+static ssize_t loaded_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&gcma_stats[LOADED_PAGE]));
+}
+GCMA_ATTR_RO(loaded);
+
+static ssize_t evicted_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&gcma_stats[EVICTED_PAGE]));
+}
+GCMA_ATTR_RO(evicted);
+
+static ssize_t cached_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&gcma_stats[CACHED_PAGE]));
+}
+GCMA_ATTR_RO(cached);
+
+static ssize_t discarded_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&gcma_stats[DISCARDED_PAGE]));
+}
+GCMA_ATTR_RO(discarded);
+
+static struct attribute *gcma_attrs[] = {
+	&stored_attr.attr,
+	&loaded_attr.attr,
+	&evicted_attr.attr,
+	&cached_attr.attr,
+	&discarded_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(gcma);
+
+static void gcma_kobj_release(struct kobject *obj)
+{
+	/* Never released the static objects */
+}
+
+static struct kobj_type gcma_ktype = {
+	.release = gcma_kobj_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = gcma_groups,
+};
+
+static int __init gcma_sysfs_init(void)
+{
+	return kobject_init_and_add(&gcma_kobj, &gcma_ktype, mm_kobj, "gcma");
+}
+subsys_initcall(gcma_sysfs_init);

mm/gcma_sysfs.h

@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __GCMA_SYSFS_H__
+#define __GCMA_SYSFS_H__
+
+enum gcma_stat_type {
+        STORED_PAGE,
+        LOADED_PAGE,
+        EVICTED_PAGE,
+        CACHED_PAGE,
+        DISCARDED_PAGE,
+        NUM_OF_GCMA_STAT,
+};
+
+#ifdef CONFIG_GCMA_SYSFS
+void gcma_stat_inc(enum gcma_stat_type type);
+void gcma_stat_dec(enum gcma_stat_type type);
+void gcma_stat_add(enum gcma_stat_type type, unsigned long delta);
+#else /* CONFIG_GCMA_SYSFS */
+static inline void gcma_stat_inc(enum gcma_stat_type type) {}
+static inline void gcma_stat_dec(enum gcma_stat_type type) {}
+static inline void gcma_stat_add(enum gcma_stat_type type,
+				 unsigned long delta) {}
+#endif /* CONFIG_GCMA_SYSFS */
+
+#endif