gpu: ion: Fix lockdep issue in ion_page_pool

Currently the mutex is held while kmalloc is called, under a low memory
condition this might trigger the shrinker which also takes this mutex.
Refactor so the mutex is not held during allocation.

Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
[jstultz: modified patch to apply to staging directory]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index ea45380..20790eb 100644 (file)
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -53,6 +53,8 @@ static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
        item = kmalloc(sizeof(struct ion_page_pool_item), GFP_KERNEL);
        if (!item)
                return -ENOMEM;
+
+       mutex_lock(&pool->mutex);
        item->page = page;
        if (PageHighMem(page)) {
                list_add_tail(&item->list, &pool->high_items);
@@ -61,6 +63,7 @@ static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
                list_add_tail(&item->list, &pool->low_items);
                pool->low_count++;
        }
+       mutex_unlock(&pool->mutex);
        return 0;
 }
 
@@ -110,9 +113,7 @@ void ion_page_pool_free(struct ion_page_pool *pool, struct page* page)
 {
        int ret;
 
-       mutex_lock(&pool->mutex);
        ret = ion_page_pool_add(pool, page);
-       mutex_unlock(&pool->mutex);
        if (ret)
                ion_page_pool_free_pages(pool, page);
 }