[PATCH 4/5] drm/i915: Show who pinned the pages when a leak is hit
Chris Wilson
chris at chris-wilson.co.uk
Wed Jul 4 07:14:35 UTC 2018
Currently, we emit a warning when freeing an object if we do so with the
pages still pinned (presumably as they are still in use somewhere). This
only tells us that there is a problem, but doesn't tell us anything
about the object or who might be pinning them and so provides no clue as
to track down the problem.
Let's try tracking everyone who pins the pages to see if we strike it
lucky and catch the culprit red handed.
v2: Suppress oom warnings, they will happen given sufficient abuse.
References: https://bugs.freedesktop.org/show_bug.cgi?id=105360
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
drivers/gpu/drm/i915/Kconfig.debug | 1 +
drivers/gpu/drm/i915/i915_drv.h | 2 +
drivers/gpu/drm/i915/i915_gem.c | 5 +-
drivers/gpu/drm/i915/i915_gem_object.c | 109 +++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_gem_object.h | 34 ++++++++
5 files changed, 150 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
index 9de8b1c51a5c..84052becb279 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -43,6 +43,7 @@ config DRM_I915_DEBUG_GEM
bool "Insert extra checks into the GEM internals"
default n
depends on DRM_I915_WERROR
+ select STACKDEPOT
help
Enable extra sanity checks (including BUGs) along the GEM driver
paths that may slow the system down and if hit hang the machine.
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 2cefe4c30f88..cc334a0fc91d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2990,6 +2990,8 @@ i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
{
might_lock(&obj->mm.lock);
+ track_i915_gem_object_pin_pages(obj);
+
if (atomic_inc_not_zero(&obj->mm.pages_pin_count))
return 0;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 048b722cf27c..749f5f5a31f8 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2465,6 +2465,7 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj,
if (!IS_ERR(pages))
obj->ops->put_pages(obj, pages);
+ untrack_i915_gem_object_pin_pages(obj);
unlock:
mutex_unlock(&obj->mm.lock);
}
@@ -4876,8 +4877,10 @@ static void __i915_gem_free_objects(struct drm_i915_private *i915,
if (obj->ops->release)
obj->ops->release(obj);
- if (WARN_ON(i915_gem_object_has_pinned_pages(obj)))
+ if (WARN_ON(i915_gem_object_has_pinned_pages(obj))) {
+ show_i915_gem_object_pin_pages(obj);
atomic_set(&obj->mm.pages_pin_count, 0);
+ }
__i915_gem_object_put_pages(obj, I915_MM_NORMAL);
GEM_BUG_ON(i915_gem_object_has_pages(obj));
diff --git a/drivers/gpu/drm/i915/i915_gem_object.c b/drivers/gpu/drm/i915/i915_gem_object.c
index aab8cdd80e6d..39b1e84bf494 100644
--- a/drivers/gpu/drm/i915/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/i915_gem_object.c
@@ -25,6 +25,115 @@
#include "i915_drv.h"
#include "i915_gem_object.h"
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+
+#include <linux/sort.h>
+
+#define STACKDEPTH 12
+
+void track_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
+{
+ unsigned long entries[STACKDEPTH];
+ struct stack_trace trace = {
+ .entries = entries,
+ .max_entries = ARRAY_SIZE(entries),
+ .skip = 1
+ };
+ unsigned long flags;
+ depot_stack_handle_t stack, *stacks;
+
+ save_stack_trace(&trace);
+ if (trace.nr_entries &&
+ trace.entries[trace.nr_entries - 1] == ULONG_MAX)
+ trace.nr_entries--;
+
+ stack = depot_save_stack(&trace, GFP_KERNEL | __GFP_NOWARN);
+ if (!stack)
+ return;
+
+ spin_lock_irqsave(&obj->mm.debug_lock, flags);
+ stacks = krealloc(obj->mm.debug_owners,
+ (obj->mm.debug_count + 1) * sizeof(*stacks),
+ GFP_NOWAIT | __GFP_NOWARN);
+ if (stacks) {
+ stacks[obj->mm.debug_count++] = stack;
+ obj->mm.debug_owners = stacks;
+ }
+ spin_unlock_irqrestore(&obj->mm.debug_lock, flags);
+}
+
+void untrack_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
+{
+ depot_stack_handle_t *stacks;
+ unsigned long flags;
+
+ spin_lock_irqsave(&obj->mm.debug_lock, flags);
+ stacks = fetch_and_zero(&obj->mm.debug_owners);
+ obj->mm.debug_count = 0;
+ spin_unlock_irqrestore(&obj->mm.debug_lock, flags);
+
+ kfree(stacks);
+}
+
+static int cmphandle(const void *_a, const void *_b)
+{
+ const depot_stack_handle_t * const a = _a, * const b = _b;
+
+ if (*a < *b)
+ return -1;
+ else if (*a > *b)
+ return 1;
+ else
+ return 0;
+}
+
+void show_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
+{
+ unsigned long entries[STACKDEPTH];
+ depot_stack_handle_t *stacks;
+ unsigned long flags, count, i;
+ char *buf;
+
+ spin_lock_irqsave(&obj->mm.debug_lock, flags);
+ stacks = fetch_and_zero(&obj->mm.debug_owners);
+ count = fetch_and_zero(&obj->mm.debug_count);
+ spin_unlock_irqrestore(&obj->mm.debug_lock, flags);
+ if (!count)
+ return;
+
+ DRM_DEBUG_DRIVER("obj %p leaked pages, pinned %lu\n", obj, count);
+
+ buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!buf)
+ goto out_stacks;
+
+ sort(stacks, count, sizeof(*stacks), cmphandle, NULL);
+
+ for (i = 0; i < count; i++) {
+ struct stack_trace trace = {
+ .entries = entries,
+ .max_entries = ARRAY_SIZE(entries),
+ };
+ depot_stack_handle_t stack = stacks[i];
+ unsigned long rep;
+
+ rep = 1;
+ while (i + 1 < count && stacks[i + 1] == stack)
+ rep++, i++;
+
+ depot_fetch_stack(stack, &trace);
+ snprint_stack_trace(buf, PAGE_SIZE, &trace, 0);
+ DRM_DEBUG_DRIVER("obj %p pages pinned x%lu at\n%s",
+ obj, rep, buf);
+ }
+
+ kfree(buf);
+out_stacks:
+ kfree(stacks);
+}
+
+#endif
+
/**
* Mark up the object's coherency levels for a given cache_level
* @obj: #drm_i915_gem_object
diff --git a/drivers/gpu/drm/i915/i915_gem_object.h b/drivers/gpu/drm/i915/i915_gem_object.h
index c3c6f2e588fb..ebc2ee17426f 100644
--- a/drivers/gpu/drm/i915/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/i915_gem_object.h
@@ -26,6 +26,9 @@
#define __I915_GEM_OBJECT_H__
#include <linux/reservation.h>
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+#include <linux/stackdepot.h>
+#endif
#include <drm/drm_vma_manager.h>
#include <drm/drm_gem.h>
@@ -245,6 +248,12 @@ struct drm_i915_gem_object {
* swizzling.
*/
bool quirked:1;
+
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+ spinlock_t debug_lock;
+ unsigned long debug_count;
+ depot_stack_handle_t *debug_owners;
+#endif
} mm;
/** Breadcrumb of last rendering to the buffer.
@@ -451,6 +460,31 @@ i915_gem_object_get_tile_row_size(struct drm_i915_gem_object *obj)
int i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
unsigned int tiling, unsigned int stride);
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
+
+void track_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj);
+void untrack_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj);
+void show_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj);
+
+#else
+
+static inline void
+track_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
+{
+}
+
+static inline void
+untrack_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
+{
+}
+
+static inline void
+show_i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
+{
+}
+
+#endif
+
static inline struct intel_engine_cs *
i915_gem_object_last_write_engine(struct drm_i915_gem_object *obj)
{
--
2.18.0
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