[PATCH 1/4] mm: cma: add currently allocated CMA buffers list to debugfs

[Stefan Strogin <s.strogin@partner.samsung.com>]

/sys/kernel/debug/cma/cma-<N>/buffers contains a list of currently allocated
CMA buffers for CMA region N when CONFIG_CMA_DEBUGFS is enabled.

Format is:

<base_phys_addr> - <end_phys_addr> (<size> kB), allocated by <PID> (<comm>)
 <stack backtrace when the buffer had been allocated>

Signed-off-by: Stefan Strogin <s.strogin@partner.samsung.com>
---
 include/linux/cma.h |   9 ++++
 mm/cma.c            |   9 ++++
 mm/cma.h            |  16 ++++++
 mm/cma_debug.c      | 145 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 178 insertions(+), 1 deletion(-)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index 9384ba6..4c2c83c 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -28,4 +28,13 @@ extern int cma_init_reserved_mem(phys_addr_t base,
 					struct cma **res_cma);
 extern struct page *cma_alloc(struct cma *cma, int count, unsigned int align);
 extern bool cma_release(struct cma *cma, struct page *pages, int count);
+
+#ifdef CONFIG_CMA_DEBUGFS
+extern int cma_buffer_list_add(struct cma *cma, unsigned long pfn, int count);
+extern void cma_buffer_list_del(struct cma *cma, unsigned long pfn, int count);
+#else
+#define cma_buffer_list_add(cma, pfn, count) { }
+#define cma_buffer_list_del(cma, pfn, count) { }
+#endif
+
 #endif
diff --git a/mm/cma.c b/mm/cma.c
index 2609e20..ed269b0 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -34,6 +34,9 @@
 #include <linux/cma.h>
 #include <linux/highmem.h>
 #include <linux/io.h>
+#include <linux/list.h>
+#include <linux/proc_fs.h>
+#include <linux/time.h>
 
 #include "cma.h"
 
@@ -125,6 +128,8 @@ static int __init cma_activate_area(struct cma *cma)
 #ifdef CONFIG_CMA_DEBUGFS
 	INIT_HLIST_HEAD(&cma->mem_head);
 	spin_lock_init(&cma->mem_head_lock);
+	INIT_LIST_HEAD(&cma->buffers_list);
+	mutex_init(&cma->list_lock);
 #endif
 
 	return 0;
@@ -408,6 +413,9 @@ struct page *cma_alloc(struct cma *cma, int count, unsigned int align)
 		start = bitmap_no + mask + 1;
 	}
 
+	if (page)
+		cma_buffer_list_add(cma, pfn, count);
+
 	pr_debug("%s(): returned %p\n", __func__, page);
 	return page;
 }
@@ -440,6 +448,7 @@ bool cma_release(struct cma *cma, struct page *pages, int count)
 
 	free_contig_range(pfn, count);
 	cma_clear_bitmap(cma, pfn, count);
+	cma_buffer_list_del(cma, pfn, count);
 
 	return true;
 }
diff --git a/mm/cma.h b/mm/cma.h
index 1132d73..98e5f79 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -1,6 +1,8 @@
 #ifndef __MM_CMA_H__
 #define __MM_CMA_H__
 
+#include <linux/sched.h>
+
 struct cma {
 	unsigned long   base_pfn;
 	unsigned long   count;
@@ -10,9 +12,23 @@ struct cma {
 #ifdef CONFIG_CMA_DEBUGFS
 	struct hlist_head mem_head;
 	spinlock_t mem_head_lock;
+	struct list_head buffers_list;
+	struct mutex	list_lock;
 #endif
 };
 
+#ifdef CONFIG_CMA_DEBUGFS
+struct cma_buffer {
+	unsigned long pfn;
+	unsigned long count;
+	pid_t pid;
+	char comm[TASK_COMM_LEN];
+	unsigned long trace_entries[16];
+	unsigned int nr_entries;
+	struct list_head list;
+};
+#endif
+
 extern struct cma cma_areas[MAX_CMA_AREAS];
 extern unsigned cma_area_count;
 
diff --git a/mm/cma_debug.c b/mm/cma_debug.c
index 7e1d325..5acd937 100644
--- a/mm/cma_debug.c
+++ b/mm/cma_debug.c
@@ -2,6 +2,7 @@
  * CMA DebugFS Interface
  *
  * Copyright (c) 2015 Sasha Levin <sasha.levin@oracle.com>
+ * Copyright (c) 2015 Stefan Strogin <stefan.strogin@gmail.com>
  */
  
 
@@ -10,6 +11,8 @@
 #include <linux/list.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/mm_types.h>
+#include <linux/stacktrace.h>
 
 #include "cma.h"
 
@@ -21,6 +24,99 @@ struct cma_mem {
 
 static struct dentry *cma_debugfs_root;
 
+/* Must be called under cma->list_lock */
+static int __cma_buffer_list_add(struct cma *cma, unsigned long pfn, int count)
+{
+	struct cma_buffer *cmabuf;
+	struct stack_trace trace;
+
+	cmabuf = kmalloc(sizeof(*cmabuf), GFP_KERNEL);
+	if (!cmabuf) {
+		pr_warn("%s(page %p, count %d): failed to allocate buffer list entry\n",
+			__func__, pfn_to_page(pfn), count);
+		return -ENOMEM;
+	}
+
+	trace.nr_entries = 0;
+	trace.max_entries = ARRAY_SIZE(cmabuf->trace_entries);
+	trace.entries = &cmabuf->trace_entries[0];
+	trace.skip = 2;
+	save_stack_trace(&trace);
+
+	cmabuf->pfn = pfn;
+	cmabuf->count = count;
+	cmabuf->pid = task_pid_nr(current);
+	cmabuf->nr_entries = trace.nr_entries;
+	get_task_comm(cmabuf->comm, current);
+
+	list_add_tail(&cmabuf->list, &cma->buffers_list);
+
+	return 0;
+}
+
+/**
+ * cma_buffer_list_add() - add a new entry to a list of allocated buffers
+ * @cma:     Contiguous memory region for which the allocation is performed.
+ * @pfn:     Base PFN of the allocated buffer.
+ * @count:   Number of allocated pages.
+ *
+ * This function adds a new entry to the list of allocated contiguous memory
+ * buffers in a CMA area. It uses the CMA area specificated by the device
+ * if available or the default global one otherwise.
+ */
+int cma_buffer_list_add(struct cma *cma, unsigned long pfn, int count)
+{
+	int ret;
+
+	mutex_lock(&cma->list_lock);
+	ret = __cma_buffer_list_add(cma, pfn, count);
+	mutex_unlock(&cma->list_lock);
+
+	return ret;
+}
+
+/**
+ * cma_buffer_list_del() - delete an entry from a list of allocated buffers
+ * @cma:   Contiguous memory region for which the allocation was performed.
+ * @pfn:   Base PFN of the released buffer.
+ * @count: Number of pages.
+ *
+ * This function deletes a list entry added by cma_buffer_list_add().
+ */
+void cma_buffer_list_del(struct cma *cma, unsigned long pfn, int count)
+{
+	struct cma_buffer *cmabuf, *tmp;
+	int found = 0;
+	unsigned long buf_end_pfn, free_end_pfn = pfn + count;
+
+	mutex_lock(&cma->list_lock);
+	list_for_each_entry_safe(cmabuf, tmp, &cma->buffers_list, list) {
+
+		buf_end_pfn = cmabuf->pfn + cmabuf->count;
+		if (pfn <= cmabuf->pfn && free_end_pfn >= buf_end_pfn) {
+			list_del(&cmabuf->list);
+			kfree(cmabuf);
+			found = 1;
+		} else if (pfn <= cmabuf->pfn && free_end_pfn < buf_end_pfn) {
+			cmabuf->count -= free_end_pfn - cmabuf->pfn;
+			cmabuf->pfn = free_end_pfn;
+			found = 1;
+		} else if (pfn > cmabuf->pfn && pfn < buf_end_pfn) {
+			if (free_end_pfn < buf_end_pfn)
+				__cma_buffer_list_add(cma, free_end_pfn,
+						buf_end_pfn - free_end_pfn);
+			cmabuf->count = pfn - cmabuf->pfn;
+			found = 1;
+		}
+	}
+	mutex_unlock(&cma->list_lock);
+
+	if (!found)
+		pr_err("%s(page %p, count %d): couldn't find buffer list entry\n",
+		       __func__, pfn_to_page(pfn), count);
+
+}
+
 static int cma_debugfs_get(void *data, u64 *val)
 {
 	unsigned long *p = data;
@@ -125,6 +221,52 @@ static int cma_alloc_write(void *data, u64 val)
 
 DEFINE_SIMPLE_ATTRIBUTE(cma_alloc_fops, NULL, cma_alloc_write, "%llu\n");
 
+static int cma_buffers_read(struct file *file, char __user *userbuf,
+				size_t count, loff_t *ppos)
+{
+	struct cma *cma = file->private_data;
+	struct cma_buffer *cmabuf;
+	struct stack_trace trace;
+	char *buf;
+	int ret, n = 0;
+
+	if (*ppos < 0 || !count)
+		return -EINVAL;
+
+	buf = kmalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	mutex_lock(&cma->list_lock);
+	list_for_each_entry(cmabuf, &cma->buffers_list, list) {
+		n += snprintf(buf + n, count - n,
+			      "0x%llx - 0x%llx (%lu kB), allocated by pid %u (%s)\n",
+			      (unsigned long long)PFN_PHYS(cmabuf->pfn),
+			      (unsigned long long)PFN_PHYS(cmabuf->pfn +
+				      cmabuf->count),
+			      (cmabuf->count * PAGE_SIZE) >> 10, cmabuf->pid,
+			      cmabuf->comm);
+
+		trace.nr_entries = cmabuf->nr_entries;
+		trace.entries = &cmabuf->trace_entries[0];
+
+		n += snprint_stack_trace(buf + n, count - n, &trace, 0);
+		n += snprintf(buf + n, count - n, "\n");
+	}
+	mutex_unlock(&cma->list_lock);
+
+	ret = simple_read_from_buffer(userbuf, count, ppos, buf, n);
+	kfree(buf);
+
+	return ret;
+}
+
+static const struct file_operations cma_buffers_fops = {
+	.open = simple_open,
+	.read = cma_buffers_read,
+	.llseek = default_llseek,
+};
+
 static void cma_debugfs_add_one(struct cma *cma, int idx)
 {       
 	struct dentry *tmp;
@@ -148,6 +290,8 @@ static void cma_debugfs_add_one(struct cma *cma, int idx)
 	debugfs_create_file("order_per_bit", S_IRUGO, tmp,
 				&cma->order_per_bit, &cma_debugfs_fops);
 
+	debugfs_create_file("buffers", S_IRUGO, tmp, cma, &cma_buffers_fops);
+
 	u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32));
 	debugfs_create_u32_array("bitmap", S_IRUGO, tmp, (u32*)cma->bitmap, u32s);
 }
@@ -166,4 +310,3 @@ static int __init cma_debugfs_init(void)
 	return 0;
 }
 late_initcall(cma_debugfs_init);
-
-- 
2.1.0

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>