Switch back to using a spinlock again by moving the IOMMU unmap outside
of the locked region.
v2: Add a comment explaining why we need sync_shrinkers().
v3: Drop sync_shrinkers() and use an SRCU instead.
Signed-off-by: Christian König <christian.koe...@amd.com>
---
drivers/gpu/drm/ttm/ttm_pool.c | 45 ++++++++++++++++++++--------------
1 file changed, 27 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
index cb38b1a17b09..cee664c487b5 100644
--- a/drivers/gpu/drm/ttm/ttm_pool.c
+++ b/drivers/gpu/drm/ttm/ttm_pool.c
@@ -70,7 +70,8 @@ static struct ttm_pool_type global_uncached[MAX_ORDER];
static struct ttm_pool_type global_dma32_write_combined[MAX_ORDER];
static struct ttm_pool_type global_dma32_uncached[MAX_ORDER];
-static struct mutex shrinker_lock;
+static spinlock_t shrinker_lock;
+DEFINE_STATIC_SRCU(shrinker_srcu);
static struct list_head shrinker_list;
static struct shrinker mm_shrinker;
@@ -263,9 +264,9 @@ static void ttm_pool_type_init(struct ttm_pool_type *pt, struct ttm_pool *pool,
spin_lock_init(&pt->lock);
INIT_LIST_HEAD(&pt->pages);
- mutex_lock(&shrinker_lock);
+ spin_lock(&shrinker_lock);
list_add_tail(&pt->shrinker_list, &shrinker_list);
- mutex_unlock(&shrinker_lock);
+ spin_unlock(&shrinker_lock);
}
/* Remove a pool_type from the global shrinker list and free all pages */
@@ -273,9 +274,9 @@ static void ttm_pool_type_fini(struct ttm_pool_type *pt)
{
struct page *p;
- mutex_lock(&shrinker_lock);
+ spin_lock(&shrinker_lock);
list_del(&pt->shrinker_list);
- mutex_unlock(&shrinker_lock);
+ spin_unlock(&shrinker_lock);
while ((p = ttm_pool_type_take(pt)))
ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
@@ -313,24 +314,27 @@ static struct ttm_pool_type *ttm_pool_select_type(struct
ttm_pool *pool,
static unsigned int ttm_pool_shrink(void)
{
struct ttm_pool_type *pt;
- unsigned int num_freed;
+ unsigned int num_pages;
struct page *p;
+ int idx;
- mutex_lock(&shrinker_lock);
+ idx = srcu_read_lock(&shrinker_srcu);
+
+ spin_lock(&shrinker_lock);
pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list);
+ list_move_tail(&pt->shrinker_list, &shrinker_list);
+ spin_unlock(&shrinker_lock);
p = ttm_pool_type_take(pt);
if (p) {
ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
- num_freed = 1 << pt->order;
+ num_pages = 1 << pt->order;
} else {
- num_freed = 0;
+ num_pages = 0;
}
- list_move_tail(&pt->shrinker_list, &shrinker_list);
- mutex_unlock(&shrinker_lock);
-
- return num_freed;
+ srcu_read_unlock(&shrinker_srcu, idx);
+ return num_pages;
}
/* Return the allocation order based for a page */
@@ -530,6 +534,11 @@ void ttm_pool_fini(struct ttm_pool *pool)
for (j = 0; j < MAX_ORDER; ++j)
ttm_pool_type_fini(&pool->caching[i].orders[j]);
}
+
+ /* We removed the pool types from the LRU, but we need to also make sure
+ * that no shrinker is concurrently freeing pages from the pool.
+ */
+ synchronize_srcu(&shrinker_srcu);
}
/* As long as pages are available make sure to release at least one */
@@ -604,7 +613,7 @@ static int ttm_pool_debugfs_globals_show(struct seq_file
*m, void *data)
{
ttm_pool_debugfs_header(m);
- mutex_lock(&shrinker_lock);
+ spin_lock(&shrinker_lock);
seq_puts(m, "wc\t:");
ttm_pool_debugfs_orders(global_write_combined, m);
seq_puts(m, "uc\t:");
@@ -613,7 +622,7 @@ static int ttm_pool_debugfs_globals_show(struct seq_file
*m, void *data)
ttm_pool_debugfs_orders(global_dma32_write_combined, m);
seq_puts(m, "uc 32\t:");
ttm_pool_debugfs_orders(global_dma32_uncached, m);
- mutex_unlock(&shrinker_lock);
+ spin_unlock(&shrinker_lock);
ttm_pool_debugfs_footer(m);
@@ -640,7 +649,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
ttm_pool_debugfs_header(m);
- mutex_lock(&shrinker_lock);
+ spin_lock(&shrinker_lock);
for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i) {
seq_puts(m, "DMA ");
switch (i) {
@@ -656,7 +665,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file
*m)
}
ttm_pool_debugfs_orders(pool->caching[i].orders, m);
}
- mutex_unlock(&shrinker_lock);
+ spin_unlock(&shrinker_lock);
ttm_pool_debugfs_footer(m);
return 0;
@@ -693,7 +702,7 @@ int ttm_pool_mgr_init(unsigned long num_pages)
if (!page_pool_size)
page_pool_size = num_pages;
- mutex_init(&shrinker_lock);
+ spin_lock_init(&shrinker_lock);
INIT_LIST_HEAD(&shrinker_list);
for (i = 0; i < MAX_ORDER; ++i) {
