1 files changed, 93 insertions, 0 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_memory.c b/drivers/gpu/drm/ttm/ttm_memory.c
index aa0c38136958..27856c55dc84 100644
--- a/drivers/gpu/drm/ttm/ttm_memory.c
+++ b/drivers/gpu/drm/ttm/ttm_memory.c
@@ -36,6 +36,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/swap.h>
 
 #define TTM_MEMORY_ALLOC_RETRIES 4
 
@@ -166,6 +167,54 @@ static struct kobj_type ttm_mem_zone_kobj_type = {
 	.default_attrs = ttm_mem_zone_attrs,
 };
 
+static struct attribute ttm_mem_global_lower_mem_limit = {
+	.name = "lower_mem_limit",
+	.mode = S_IRUGO | S_IWUSR
+};
+
+static ssize_t ttm_mem_global_show(struct kobject *kobj,
+				 struct attribute *attr,
+				 char *buffer)
+{
+	struct ttm_mem_global *glob =
+		container_of(kobj, struct ttm_mem_global, kobj);
+	uint64_t val = 0;
+
+	spin_lock(&glob->lock);
+	val = glob->lower_mem_limit;
+	spin_unlock(&glob->lock);
+	/* convert from number of pages to KB */
+	val <<= (PAGE_SHIFT - 10);
+	return snprintf(buffer, PAGE_SIZE, "%llu\n",
+			(unsigned long long) val);
+}
+
+static ssize_t ttm_mem_global_store(struct kobject *kobj,
+				  struct attribute *attr,
+				  const char *buffer,
+				  size_t size)
+{
+	int chars;
+	uint64_t val64;
+	unsigned long val;
+	struct ttm_mem_global *glob =
+		container_of(kobj, struct ttm_mem_global, kobj);
+
+	chars = sscanf(buffer, "%lu", &val);
+	if (chars == 0)
+		return size;
+
+	val64 = val;
+	/* convert from KB to number of pages */
+	val64 >>= (PAGE_SHIFT - 10);
+
+	spin_lock(&glob->lock);
+	glob->lower_mem_limit = val64;
+	spin_unlock(&glob->lock);
+
+	return size;
+}
+
 static void ttm_mem_global_kobj_release(struct kobject *kobj)
 {
 	struct ttm_mem_global *glob =
@@ -174,8 +223,20 @@ static void ttm_mem_global_kobj_release(struct kobject *kobj)
 	kfree(glob);
 }
 
+static struct attribute *ttm_mem_global_attrs[] = {
+	&ttm_mem_global_lower_mem_limit,
+	NULL
+};
+
+static const struct sysfs_ops ttm_mem_global_ops = {
+	.show = &ttm_mem_global_show,
+	.store = &ttm_mem_global_store,
+};
+
 static struct kobj_type ttm_mem_glob_kobj_type = {
 	.release = &ttm_mem_global_kobj_release,
+	.sysfs_ops = &ttm_mem_global_ops,
+	.default_attrs = ttm_mem_global_attrs,
 };
 
 static bool ttm_zones_above_swap_target(struct ttm_mem_global *glob,
@@ -375,6 +436,9 @@ int ttm_mem_global_init(struct ttm_mem_global *glob)
 
 	si_meminfo(&si);
 
+	/* set it as 0 by default to keep original behavior of OOM */
+	glob->lower_mem_limit = 0;
+
 	ret = ttm_mem_init_kernel_zone(glob, &si);
 	if (unlikely(ret != 0))
 		goto out_no_zone;
@@ -469,6 +533,35 @@ void ttm_mem_global_free(struct ttm_mem_global *glob,
 }
 EXPORT_SYMBOL(ttm_mem_global_free);
 
+/*
+ * check if the available mem is under lower memory limit
+ *
+ * a. if no swap disk at all or free swap space is under swap_mem_limit
+ * but available system mem is bigger than sys_mem_limit, allow TTM
+ * allocation;
+ *
+ * b. if the available system mem is less than sys_mem_limit but free
+ * swap disk is bigger than swap_mem_limit, allow TTM allocation.
+ */
+bool
+ttm_check_under_lowerlimit(struct ttm_mem_global *glob,
+			uint64_t num_pages,
+			struct ttm_operation_ctx *ctx)
+{
+	int64_t available;
+
+	if (ctx->flags & TTM_OPT_FLAG_FORCE_ALLOC)
+		return false;
+
+	available = get_nr_swap_pages() + si_mem_available();
+	available -= num_pages;
+	if (available < glob->lower_mem_limit)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(ttm_check_under_lowerlimit);
+
 static int ttm_mem_global_reserve(struct ttm_mem_global *glob,
 				  struct ttm_mem_zone *single_zone,
 				  uint64_t amount, bool reserve)