Hook up the shrinker for inteldrm(4). This is a "light" version that only

drops graphics buffers that are cached and not in active use.
Help from beck@ for pointing out how to hook this up to our pagedaemon.

ok jsg@

7 files changed, 77 insertions, 12 deletions

diff --git a/sys/dev/pci/drm/drm_linux.c b/sys/dev/pci/drm/drm_linux.c
index ffd8ded926d..1fb37929613 100644
--- a/sys/dev/pci/drm/drm_linux.c
+++ b/sys/dev/pci/drm/drm_linux.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: drm_linux.c,v 1.51 2019/11/30 11:19:17 visa Exp $	*/
+/*	$OpenBSD: drm_linux.c,v 1.52 2019/12/25 11:31:41 kettenis Exp $	*/
 /*
  * Copyright (c) 2013 Jonathan Gray <jsg@openbsd.org>
  * Copyright (c) 2015, 2016 Mark Kettenis <kettenis@openbsd.org>
@@ -1867,3 +1867,28 @@ pci_resize_resource(struct pci_dev *pdev, int bar, int nsize)
 
 	return 0;
 }
+
+TAILQ_HEAD(, shrinker) shrinkers = TAILQ_HEAD_INITIALIZER(shrinkers);
+
+int
+register_shrinker(struct shrinker *shrinker)
+{
+	TAILQ_INSERT_TAIL(&shrinkers, shrinker, next);
+	return 0;
+}
+
+void
+drmbackoff(long npages)
+{
+	struct shrink_control sc;
+	struct shrinker *shrinker;
+	u_long ret;
+
+	shrinker = TAILQ_FIRST(&shrinkers);
+	while (shrinker && npages > 0) {
+		sc.nr_to_scan = npages;
+		ret = shrinker->scan_objects(shrinker, &sc);
+		npages -= ret;
+		shrinker = TAILQ_NEXT(shrinker, next);
+	}
+}
diff --git a/sys/dev/pci/drm/i915/i915_drv.h b/sys/dev/pci/drm/i915/i915_drv.h
index d690cc87b87..0a40b9aac72 100644
--- a/sys/dev/pci/drm/i915/i915_drv.h
+++ b/sys/dev/pci/drm/i915/i915_drv.h
@@ -1072,9 +1072,7 @@ struct i915_gem_mm {
 
 	struct notifier_block oom_notifier;
 	struct notifier_block vmap_notifier;
-#ifdef notyet
 	struct shrinker shrinker;
-#endif
 
 	/** LRU list of objects with fence regs on them. */
 	struct list_head fence_list;
diff --git a/sys/dev/pci/drm/i915/i915_gem_shrinker.c b/sys/dev/pci/drm/i915/i915_gem_shrinker.c
index 4fd8979b7cb..8bac088399d 100644
--- a/sys/dev/pci/drm/i915/i915_gem_shrinker.c
+++ b/sys/dev/pci/drm/i915/i915_gem_shrinker.c
@@ -36,7 +36,6 @@
 #include "i915_drv.h"
 #include "i915_trace.h"
 
-#ifdef notyet
 static bool shrinker_lock(struct drm_i915_private *i915, bool *unlock)
 {
 	switch (mutex_trylock_recursive(&i915->drm.struct_mutex)) {
@@ -115,7 +114,6 @@ static bool unsafe_drop_pages(struct drm_i915_gem_object *obj)
 		__i915_gem_object_put_pages(obj, I915_MM_SHRINKER);
 	return !i915_gem_object_has_pages(obj);
 }
-#endif
 
 /**
  * i915_gem_shrink - Shrink buffer object caches
@@ -148,9 +146,6 @@ i915_gem_shrink(struct drm_i915_private *i915,
 		unsigned long *nr_scanned,
 		unsigned flags)
 {
-	STUB();
-	return -ENOSYS;
-#ifdef notyet
 	const struct {
 		struct list_head *list;
 		unsigned int bit;
@@ -280,7 +275,6 @@ i915_gem_shrink(struct drm_i915_private *i915,
 	if (nr_scanned)
 		*nr_scanned += scanned;
 	return count;
-#endif
 }
 
 /**
@@ -311,7 +305,6 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *i915)
 	return freed;
 }
 
-#ifdef notyet
 static unsigned long
 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 {
@@ -393,6 +386,7 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 	return sc->nr_scanned ? freed : SHRINK_STOP;
 }
 
+#ifdef notyet
 static bool
 shrinker_lock_uninterruptible(struct drm_i915_private *i915, bool *unlock,
 			      int timeout_ms)
@@ -513,13 +507,13 @@ out:
  */
 void i915_gem_shrinker_register(struct drm_i915_private *i915)
 {
-#ifdef notyet
 	i915->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
 	i915->mm.shrinker.count_objects = i915_gem_shrinker_count;
 	i915->mm.shrinker.seeks = DEFAULT_SEEKS;
 	i915->mm.shrinker.batch = 4096;
 	WARN_ON(register_shrinker(&i915->mm.shrinker));
 
+#ifdef notyet
 	i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 	WARN_ON(register_oom_notifier(&i915->mm.oom_notifier));
 
diff --git a/sys/dev/pci/drm/include/linux/mm.h b/sys/dev/pci/drm/include/linux/mm.h
index da4080289ba..3d38297afbd 100644
--- a/sys/dev/pci/drm/include/linux/mm.h
+++ b/sys/dev/pci/drm/include/linux/mm.h
@@ -11,6 +11,7 @@
 #include <machine/cpu.h>
 #include <uvm/uvm_extern.h>
 #include <linux/fs.h>
+#include <linux/shrinker.h>
 #include <asm/pgtable.h>
 
 #define unmap_mapping_range(mapping, holebegin, holeend, even_cows)
diff --git a/sys/dev/pci/drm/include/linux/mutex.h b/sys/dev/pci/drm/include/linux/mutex.h
index ec0abdbbe69..a1436f82228 100644
--- a/sys/dev/pci/drm/include/linux/mutex.h
+++ b/sys/dev/pci/drm/include/linux/mutex.h
@@ -16,7 +16,23 @@
 #define mutex_lock_nested(rwl, sub)	rw_enter_write(rwl)
 #define mutex_trylock(rwl)		(rw_enter(rwl, RW_WRITE | RW_NOSLEEP) == 0)
 #define mutex_unlock(rwl)		rw_exit_write(rwl)
-#define mutex_is_locked(rwl)		(rw_status(rwl) == RW_WRITE)
+#define mutex_is_locked(rwl)		(rw_status(rwl) != 0)
 #define mutex_destroy(rwl)
 
+enum mutex_trylock_recursive_result {
+	MUTEX_TRYLOCK_FAILED,
+	MUTEX_TRYLOCK_SUCCESS,
+	MUTEX_TRYLOCK_RECURSIVE
+};
+
+static inline enum mutex_trylock_recursive_result
+mutex_trylock_recursive(struct rwlock *rwl)
+{
+	if (rw_status(rwl) == RW_WRITE)
+		return MUTEX_TRYLOCK_RECURSIVE;
+	if (mutex_trylock(rwl))
+		return MUTEX_TRYLOCK_SUCCESS;
+	return MUTEX_TRYLOCK_FAILED;
+}
+
 #endif
diff --git a/sys/dev/pci/drm/include/linux/shrinker.h b/sys/dev/pci/drm/include/linux/shrinker.h
new file mode 100644
index 00000000000..12d36810d46
--- /dev/null
+++ b/sys/dev/pci/drm/include/linux/shrinker.h
@@ -0,0 +1,25 @@
+/* Public domain. */
+
+#ifndef _LINUX_SHRINKER_H
+#define _LINUX_SHRINKER_H
+
+struct shrink_control {
+	u_long	nr_to_scan;
+	u_long	nr_scanned;
+};
+
+struct shrinker {
+	u_long	(*count_objects)(struct shrinker *, struct shrink_control *);
+	u_long	(*scan_objects)(struct shrinker *, struct shrink_control *);
+	long	batch;
+	int	seeks;
+	TAILQ_ENTRY(shrinker) next;
+};
+
+#define SHRINK_STOP	~0UL
+
+#define DEFAULT_SEEKS	2
+
+int register_shrinker(struct shrinker *);
+
+#endif
diff --git a/sys/dev/pci/drm/include/linux/swap.h b/sys/dev/pci/drm/include/linux/swap.h
index 98827081640..ce2f8ad9378 100644
--- a/sys/dev/pci/drm/include/linux/swap.h
+++ b/sys/dev/pci/drm/include/linux/swap.h
@@ -11,4 +11,10 @@ get_nr_swap_pages(void)
 	return uvmexp.swpages - uvmexp.swpginuse;
 }
 
+/* 
+ * XXX For now, we don't want the shrinker to be too aggressive, so
+ * pretend we're not called from the pagedaemon even if we are.
+ */
+#define current_is_kswapd()	0
+
 #endif