From v2 - https://lore.kernel.org/linux-mm/20210208180142.2765456-1-minchan@xxxxxxxxxx/
* sysfs doc and description modification - jhubbard
From v1 - https://lore.kernel.org/linux-mm/20210203155001.4121868-1-minchan@xxxxxxxxxx/
* fix sysfs build and refactoring - willy
* rename and drop some attributes - jhubbard
Documentation/ABI/testing/sysfs-kernel-mm-cma | 25 ++++
mm/Kconfig | 7 ++
mm/Makefile | 1 +
mm/cma.c | 6 +-
mm/cma.h | 18 +++
mm/cma_sysfs.c | 114 ++++++++++++++++++
6 files changed, 170 insertions(+), 1 deletion(-)
create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-cma
create mode 100644 mm/cma_sysfs.c
diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-cma b/Documentation/ABI/testing/sysfs-kernel-mm-cma
new file mode 100644
index 000000000000..f518af819cee
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-cma
@@ -0,0 +1,25 @@
+What: /sys/kernel/mm/cma/
+Date: Feb 2021
+Contact: Minchan Kim <minchan@xxxxxxxxxx>
+Description:
+ /sys/kernel/mm/cma/ contains a subdirectory for each CMA
+ heap name (also sometimes called CMA areas).
+
+ Each CMA heap subdirectory (that is, each
+ /sys/kernel/mm/cma/<cma-heap-name> directory) contains the
+ following items:
+
+ cma_alloc_pages_attempts
+ cma_alloc_pages_fails
+
+What: /sys/kernel/mm/cma/<cma-heap-name>/cma_alloc_pages_attempts
+Date: Feb 2021
+Contact: Minchan Kim <minchan@xxxxxxxxxx>
+Description:
+ the number of pages CMA API tried to allocate
+
+What: /sys/kernel/mm/cma/<cma-heap-name>/cma_alloc_pages_fails
+Date: Feb 2021
+Contact: Minchan Kim <minchan@xxxxxxxxxx>
+Description:
+ the number of pages CMA API failed to allocate
diff --git a/mm/Kconfig b/mm/Kconfig
index ec35bf406439..ad7e9c065657 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -513,6 +513,13 @@ config CMA_DEBUGFS
help
Turns on the DebugFS interface for CMA.
+config CMA_SYSFS
+ bool "CMA information through sysfs interface"
+ depends on CMA && SYSFS
+ help
+ This option exposes some sysfs attributes to get information
+ from CMA.
+
config CMA_AREAS
int "Maximum count of the CMA areas"
depends on CMA
diff --git a/mm/Makefile b/mm/Makefile
index b2a564eec27f..e10c14300191 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -109,6 +109,7 @@ obj-$(CONFIG_CMA) += cma.o
obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
+obj-$(CONFIG_CMA_SYSFS) += cma_sysfs.o
obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o
obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o
diff --git a/mm/cma.c b/mm/cma.c
index 23d4a97c834a..b42ccafc71e5 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -447,9 +447,10 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
offset = cma_bitmap_aligned_offset(cma, align);
bitmap_maxno = cma_bitmap_maxno(cma);
bitmap_count = cma_bitmap_pages_to_bits(cma, count);
+ cma_sysfs_alloc_count(cma, count);
if (bitmap_count > bitmap_maxno)
- return NULL;
+ goto out;
for (;;) {
mutex_lock(&cma->lock);
@@ -504,6 +505,9 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
__func__, count, ret);
cma_debug_show_areas(cma);
}
+out:
+ if (!page)
+ cma_sysfs_fail_count(cma, count);
pr_debug("%s(): returned %p\n", __func__, page);
return page;
diff --git a/mm/cma.h b/mm/cma.h
index 42ae082cb067..24a1d61eabc7 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -3,6 +3,14 @@
#define __MM_CMA_H__
#include <linux/debugfs.h>
+#include <linux/kobject.h>
+
+struct cma_stat {
+ spinlock_t lock;
+ unsigned long pages_attempts; /* the number of CMA page allocation attempts */
+ unsigned long pages_fails; /* the number of CMA page allocation failures */
+ struct kobject kobj;
+};
struct cma {
unsigned long base_pfn;
@@ -16,6 +24,9 @@ struct cma {
struct debugfs_u32_array dfs_bitmap;
#endif
char name[CMA_MAX_NAME];
+#ifdef CONFIG_CMA_SYSFS
+ struct cma_stat *stat;
+#endif
};
extern struct cma cma_areas[MAX_CMA_AREAS];
@@ -26,4 +37,11 @@ static inline unsigned long cma_bitmap_maxno(struct cma *cma)
return cma->count >> cma->order_per_bit;
}
+#ifdef CONFIG_CMA_SYSFS
+void cma_sysfs_alloc_count(struct cma *cma, size_t count);
+void cma_sysfs_fail_count(struct cma *cma, size_t count);
+#else
+static inline void cma_sysfs_alloc_count(struct cma *cma, size_t count) {};
+static inline void cma_sysfs_fail_count(struct cma *cma, size_t count) {};
+#endif
#endif
diff --git a/mm/cma_sysfs.c b/mm/cma_sysfs.c
new file mode 100644
index 000000000000..d281bf95a614
--- /dev/null
+++ b/mm/cma_sysfs.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * CMA SysFS Interface
+ *
+ * Copyright (c) 2021 Minchan Kim <minchan@xxxxxxxxxx>
+ */
+
+#include <linux/cma.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "cma.h"
+
+static struct cma_stat *cma_stats;
+
+void cma_sysfs_alloc_count(struct cma *cma, size_t count)
+{
+ spin_lock(&cma->stat->lock);
+ cma->stat->pages_attempts += count;
+ spin_unlock(&cma->stat->lock);
+}
+
+void cma_sysfs_fail_count(struct cma *cma, size_t count)
+{
+ spin_lock(&cma->stat->lock);
+ cma->stat->pages_fails += count;
+ spin_unlock(&cma->stat->lock);
+}
+
+#define CMA_ATTR_RO(_name) \
+ static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+
+static struct kobject *cma_kobj;
+
+static ssize_t cma_alloc_pages_attempts_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct cma_stat *stat = container_of(kobj, struct cma_stat, kobj);
+
+ return sysfs_emit(buf, "%lu\n", stat->pages_attempts);
+}
+CMA_ATTR_RO(cma_alloc_pages_attempts);
+
+static ssize_t cma_alloc_pages_fails_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct cma_stat *stat = container_of(kobj, struct cma_stat, kobj);
+
+ return sysfs_emit(buf, "%lu\n", stat->pages_fails);
+}
+CMA_ATTR_RO(cma_alloc_pages_fails);
+
+static void cma_kobj_release(struct kobject *kobj)
+{
+ struct cma_stat *stat = container_of(kobj, struct cma_stat, kobj);
+
+ kfree(stat);
+}
+
+static struct attribute *cma_attrs[] = {
+ &cma_alloc_pages_attempts_attr.attr,
+ &cma_alloc_pages_fails_attr.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(cma);
+
+static struct kobj_type cma_ktype = {
+ .release = cma_kobj_release,
+ .sysfs_ops = &kobj_sysfs_ops,
+ .default_groups = cma_groups
+};
+
+static int __init cma_sysfs_init(void)
+{
+ int i = 0;
+ struct cma *cma;
+
+ cma_kobj = kobject_create_and_add("cma", mm_kobj);
+ if (!cma_kobj) {
+ pr_err("failed to create cma kobject\n");
+ return -ENOMEM;
+ }
+
+ cma_stats = kzalloc(array_size(sizeof(struct cma_stat),
+ cma_area_count), GFP_KERNEL);
+ if (!cma_stats) {
+ pr_err("failed to create cma_stats\n");
+ goto out;
+ }
+
+ do {
+ cma = &cma_areas[i];
+ cma->stat = &cma_stats[i];
+ spin_lock_init(&cma->stat->lock);
+ if (kobject_init_and_add(&cma->stat->kobj, &cma_ktype,
+ cma_kobj, "%s", cma->name)) {
+ kobject_put(&cma->stat->kobj);
+ goto out;
+ }
+ } while (++i < cma_area_count);
+
+ return 0;
+out:
+ while (--i >= 0) {
+ cma = &cma_areas[i];
+ kobject_put(&cma->stat->kobj);
+ }
+
+ kfree(cma_stats);
+ kobject_put(cma_kobj);
+
+ return -ENOMEM;
+}
+subsys_initcall(cma_sysfs_init);
