We can use the kernel's stack tracer and depot to record the allocation
site of every drm_mm user and then on shutdown as well as warning that
allocated nodes still reside with the drm_mm range manager, we can also
display who allocated them to aide tracking down the leak.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/Kconfig | 12 ++++++++
drivers/gpu/drm/drm_mm.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++--
include/drm/drm_mm.h | 6 ++++
3 files changed, 89 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 483059a22b1b..e339ac9ca8cf 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -300,3 +300,15 @@ config DRM_SAVAGE
chipset. If M is selected the module will be called savage.
endif # DRM_LEGACY
+
+config DRM_DEBUG_MM
+ bool "Insert extra checks for tracking the memory manager"
+ default n
+ depends on DRM
+ select STACKDEPOT
+ help
+ Enable tracking of memory manager and leak detection.
+
+ Recommended for driver developers only.
+
+ If in doubt, say "N".
diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 11d44a1e0ab3..f7d25c02297d 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -104,6 +104,66 @@ static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_
u64 end,
enum drm_mm_search_flags flags);
+#if CONFIG_DRM_DEBUG_MM
+#define STACKDEPTH 32
+#define BUFSZ 4096
+
+static noinline void save_stack(struct drm_mm_node *node)
+{
+ unsigned long entries[STACKDEPTH];
+ struct stack_trace trace = {
+ .entries = entries,
+ .max_entries = STACKDEPTH,
+ .skip = 1
+ };
+
+ save_stack_trace(&trace);
+ if (trace.nr_entries != 0 &&
+ trace.entries[trace.nr_entries-1] == ULONG_MAX)
+ trace.nr_entries--;
+
+ /* May be called under spinlock, so avoid sleeping */
+ node->stack = depot_save_stack(&trace, GFP_NOWAIT);
+}
+
+static void show_leaks(struct drm_mm *mm)
+{
+ struct drm_mm_node *node;
+ unsigned long entries[STACKDEPTH];
+ char *buf;
+
+ buf = kmalloc(BUFSZ, GFP_KERNEL);
+ if (!buf)
+ return;
+
+ list_for_each_entry(node, &mm->head_node.node_list, node_list) {
+ struct stack_trace trace = {
+ .entries = entries,
+ .max_entries = STACKDEPTH
+ };
+
+ if (!node->stack) {
+ DRM_ERROR("node [%08llx + %08llx]: unknown owner\n",
+ node->start, node->size);
+ continue;
+ }
+
+ depot_fetch_stack(node->stack, &trace);
+ snprint_stack_trace(buf, BUFSZ, &trace, 0);
+ DRM_ERROR("node [%08llx + %08llx]: inserted at\n%s",
+ node->start, node->size, buf);
+ }
+
+ kfree(buf);
+}
+
+#undef STACKDEPTH
+#undef BUFSZ
+#else
+static void save_stack(struct drm_mm_node *node) { }
+static void show_leaks(struct drm_mm *mm) { }
+#endif
+
#define START(node) ((node)->start)
#define LAST(node) ((node)->start + (node)->size - 1)
@@ -228,6 +288,8 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
list_add(&node->hole_stack, &mm->hole_stack);
node->hole_follows = 1;
}
+
+ save_stack(node);
}
/**
@@ -293,6 +355,8 @@ int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
node->hole_follows = 1;
}
+ save_stack(node);
+
return 0;
}
EXPORT_SYMBOL(drm_mm_reserve_node);
@@ -397,6 +461,8 @@ static void drm_mm_insert_helper_range(struct drm_mm_node *hole_node,
list_add(&node->hole_stack, &mm->hole_stack);
node->hole_follows = 1;
}
+
+ save_stack(node);
}
/**
@@ -861,10 +927,12 @@ EXPORT_SYMBOL(drm_mm_init);
* Note that it is a bug to call this function on an allocator which is not
* clean.
*/
-void drm_mm_takedown(struct drm_mm * mm)
+void drm_mm_takedown(struct drm_mm *mm)
{
- WARN(!list_empty(&mm->head_node.node_list),
- "Memory manager not clean during takedown.\n");
+ if (WARN(!list_empty(&mm->head_node.node_list),
+ "Memory manager not clean during takedown.\n"))
+ show_leaks(mm);
+
}
EXPORT_SYMBOL(drm_mm_takedown);
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index 205ddcf6d55d..41ddafe92b2f 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -44,6 +44,9 @@
#ifdef CONFIG_DEBUG_FS
#include <linux/seq_file.h>
#endif
+#ifdef CONFIG_DRM_DEBUG_MM
+#include <linux/stackdepot.h>
+#endif
enum drm_mm_search_flags {
DRM_MM_SEARCH_DEFAULT = 0,
@@ -74,6 +77,9 @@ struct drm_mm_node {
u64 size;
u64 __subtree_last;
struct drm_mm *mm;
+#ifdef CONFIG_DRM_DEBUG_MM
+ depot_stack_handle_t stack;
+#endif
};
struct drm_mm {
--
2.10.1
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