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

From: SeongJae Park
Date: Fri Feb 13 2015 - 09:16:40 EST

Hello, Stefan.

On Fri, 13 Feb 2015, Stefan Strogin wrote:

/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@xxxxxxxxxxxxxxxxxxx>
---
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>

Looks like `proc_fs.h` and `time.h` are not necessary.


#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@xxxxxxxxxx>
+ * Copyright (c) 2015 Stefan Strogin <stefan.strogin@xxxxxxxxx>
*/


@@ -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);

pfn_to_page() would cause build failure on x86_64. Why don't you include appropriate header file?


Thanks,
SeongJae Park

+ 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


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