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Subject[PATCH 040/115] gpu: ion: Fix lockdep issue in ion_page_pool
Date
From: Rebecca Schultz Zavin <rebecca@android.com>

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>
---
drivers/staging/android/ion/ion_page_pool.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index ea45380..20790eb 100644
--- 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);
}
--
1.8.3.2


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