From 43ca106fa8ec7d684776fbe561214d3b2b7cb9cb Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Tue, 4 May 2021 18:37:28 -0700
Subject: [PATCH] mm: cma: support sysfs
Since CMA is getting used more widely, it's more important to keep
monitoring CMA statistics for system health since it's directly related to
user experience.
This patch introduces sysfs statistics for CMA, in order to provide some
basic monitoring of the CMA allocator.
* the number of CMA page successful allocations
* the number of CMA page allocation failures
These two values allow the user to calcuate the allocation
failure rate for each CMA area.
e.g.)
/sys/kernel/mm/cma/WIFI/alloc_pages_[success|fail]
/sys/kernel/mm/cma/SENSOR/alloc_pages_[success|fail]
/sys/kernel/mm/cma/BLUETOOTH/alloc_pages_[success|fail]
The cma_stat was intentionally allocated by dynamic allocation
to harmonize with kobject lifetime management.
https://lore.kernel.org/linux-mm/YCOAmXqt6dZkCQYs@kroah.com/
Link: https://lkml.kernel.org/r/20210324230759.2213957-1-minchan@kernel.org
Link: https://lore.kernel.org/linux-mm/20210316100433.17665-1-colin.king@canonical.com/
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: John Dias <joaodias@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Documentation/ABI/testing/sysfs-kernel-mm-cma | 25 ++++
mm/Kconfig | 7 ++
mm/Makefile | 1 +
mm/cma.c | 8 +-
mm/cma.h | 23 ++++
mm/cma_sysfs.c | 112 ++++++++++++++++++
6 files changed, 174 insertions(+), 2 deletions(-)
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 0000000000000..02b2bb60c2969
--- /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@kernel.org>
+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:
+
+ alloc_pages_success
+ alloc_pages_fail
+
+What: /sys/kernel/mm/cma/<cma-heap-name>/alloc_pages_success
+Date: Feb 2021
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ the number of pages CMA API succeeded to allocate
+
+What: /sys/kernel/mm/cma/<cma-heap-name>/alloc_pages_fail
+Date: Feb 2021
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ the number of pages CMA API failed to allocate
diff --git a/mm/Kconfig b/mm/Kconfig
index f4ceeaedb9661..5f7d7b3d8cc29 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -518,6 +518,13 @@ 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 c0135e385984b..809033d77710c 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 d1a4c06b50397..2380f2571eb53 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -511,10 +511,14 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
pr_debug("%s(): returned %p\n", __func__, page);
out:
- if (page)
+ if (page) {
count_vm_event(CMA_ALLOC_SUCCESS);
- else
+ cma_sysfs_account_success_pages(cma, count);
+ } else {
count_vm_event(CMA_ALLOC_FAIL);
+ if (cma)
+ cma_sysfs_account_fail_pages(cma, count);
+ }
return page;
}
diff --git a/mm/cma.h b/mm/cma.h
index c46c5050aaa90..2c775877eae24 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -3,6 +3,12 @@
#define __MM_CMA_H__
#include <linux/debugfs.h>
+#include <linux/kobject.h>
+
+struct cma_kobject {
+ struct kobject kobj;
+ struct cma *cma;
+};
struct cma {
unsigned long base_pfn;
@@ -16,6 +22,14 @@ struct cma {
struct debugfs_u32_array dfs_bitmap;
#endif
char name[CMA_MAX_NAME];
+#ifdef CONFIG_CMA_SYSFS
+ /* the number of CMA page successful allocations */
+ atomic64_t nr_pages_succeeded;
+ /* the number of CMA page allocation failures */
+ atomic64_t nr_pages_failed;
+ /* kobject requires dynamic object */
+ struct cma_kobject *cma_kobj;
+#endif
};
extern struct cma cma_areas[MAX_CMA_AREAS];
@@ -26,4 +40,13 @@ static inline unsigned long cma_bitmap_maxno(struct cma *cma)
return cma->count >> cma->order_per_bit;
}
+#ifdef CONFIG_CMA_SYSFS
+void cma_sysfs_account_success_pages(struct cma *cma, unsigned long nr_pages);
+void cma_sysfs_account_fail_pages(struct cma *cma, unsigned long nr_pages);
+#else
+static inline void cma_sysfs_account_success_pages(struct cma *cma,
+ unsigned long nr_pages) {};
+static inline void cma_sysfs_account_fail_pages(struct cma *cma,
+ unsigned long nr_pages) {};
+#endif
#endif
diff --git a/mm/cma_sysfs.c b/mm/cma_sysfs.c
new file mode 100644
index 0000000000000..eb2f39caff59b
--- /dev/null
+++ b/mm/cma_sysfs.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * CMA SysFS Interface
+ *
+ * Copyright (c) 2021 Minchan Kim <minchan@kernel.org>
+ */
+
+#include <linux/cma.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "cma.h"
+
+#define CMA_ATTR_RO(_name) \
+ static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+
+void cma_sysfs_account_success_pages(struct cma *cma, unsigned long nr_pages)
+{
+ atomic64_add(nr_pages, &cma->nr_pages_succeeded);
+}
+
+void cma_sysfs_account_fail_pages(struct cma *cma, unsigned long nr_pages)
+{
+ atomic64_add(nr_pages, &cma->nr_pages_failed);
+}
+
+static inline struct cma *cma_from_kobj(struct kobject *kobj)
+{
+ return container_of(kobj, struct cma_kobject, kobj)->cma;
+}
+
+static ssize_t alloc_pages_success_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct cma *cma = cma_from_kobj(kobj);
+
+ return sysfs_emit(buf, "%llu\n",
+ atomic64_read(&cma->nr_pages_succeeded));
+}
+CMA_ATTR_RO(alloc_pages_success);
+
+static ssize_t alloc_pages_fail_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct cma *cma = cma_from_kobj(kobj);
+
+ return sysfs_emit(buf, "%llu\n", atomic64_read(&cma->nr_pages_failed));
+}
+CMA_ATTR_RO(alloc_pages_fail);
+
+static void cma_kobj_release(struct kobject *kobj)
+{
+ struct cma *cma = cma_from_kobj(kobj);
+ struct cma_kobject *cma_kobj = cma->cma_kobj;
+
+ kfree(cma_kobj);
+ cma->cma_kobj = NULL;
+}
+
+static struct attribute *cma_attrs[] = {
+ &alloc_pages_success_attr.attr,
+ &alloc_pages_fail_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)
+{
+ struct kobject *cma_kobj_root;
+ struct cma_kobject *cma_kobj;
+ struct cma *cma;
+ int i, err;
+
+ cma_kobj_root = kobject_create_and_add("cma", mm_kobj);
+ if (!cma_kobj_root)
+ return -ENOMEM;
+
+ for (i = 0; i < cma_area_count; i++) {
+ cma_kobj = kzalloc(sizeof(*cma_kobj), GFP_KERNEL);
+ if (!cma_kobj) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ cma = &cma_areas[i];
+ cma->cma_kobj = cma_kobj;
+ cma_kobj->cma = cma;
+ err = kobject_init_and_add(&cma_kobj->kobj, &cma_ktype,
+ cma_kobj_root, "%s", cma->name);
+ if (err) {
+ kobject_put(&cma_kobj->kobj);
+ goto out;
+ }
+ }
+
+ return 0;
+out:
+ while (--i >= 0) {
+ cma = &cma_areas[i];
+ kobject_put(&cma->cma_kobj->kobj);
+ }
+ kobject_put(cma_kobj_root);
+
+ return err;
+}
+subsys_initcall(cma_sysfs_init);
--
GitLab