linux-kernel - [PATCH v3 1/2] staging: android: Remove BUG_ON from ion_page

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Date:   Wed, 19 Aug 2020 22:38:47 +0300
From:   Tomer Samara <tomersamara98@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Arve Hjønnevåg <arve@...roid.com>,
        Riley Andrews <riandrews@...roid.com>,
        Laura Abbott <labbott@...hat.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Todd Kjos <tkjos@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Christian Brauner <christian@...uner.io>,
        Hridya Valsaraju <hridya@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        devel@...verdev.osuosl.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/2] staging: android: Remove BUG_ON from ion_page_pool.c

BUG_ON() is removed at ion_page_pool.c and add error handleing to
ion_page_pool_shrink

Fixes the following issue:
Avoid crashing the kernel - try using WARN_ON & recovery code ratherthan BUG() or BUG_ON().

Signed-off-by: Tomer Samara <tomersamara98@...il.com>
---
 drivers/staging/android/ion/ion_page_pool.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 0198b886d906..ae2bc57bcbe8 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -46,11 +46,13 @@ static struct page *ion_page_pool_remove(struct ion_page_pool *pool, bool high)
 	struct page *page;
 
 	if (high) {
-		BUG_ON(!pool->high_count);
+		if (!pool->high_count)
+			return NULL;
 		page = list_first_entry(&pool->high_items, struct page, lru);
 		pool->high_count--;
 	} else {
-		BUG_ON(!pool->low_count);
+		if (!pool->low_count)
+			return NULL;
 		page = list_first_entry(&pool->low_items, struct page, lru);
 		pool->low_count--;
 	}
@@ -65,7 +67,8 @@ struct page *ion_page_pool_alloc(struct ion_page_pool *pool)
 {
 	struct page *page = NULL;
 
-	BUG_ON(!pool);
+	if (!pool)
+		return NULL;
 
 	mutex_lock(&pool->mutex);
 	if (pool->high_count)
@@ -82,7 +85,8 @@ struct page *ion_page_pool_alloc(struct ion_page_pool *pool)
 
 void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
 {
-	BUG_ON(pool->order != compound_order(page));
+	if (pool->order != compound_order(page))
+		return;
 
 	ion_page_pool_add(pool, page);
 }
@@ -124,6 +128,8 @@ int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 			break;
 		}
 		mutex_unlock(&pool->mutex);
+		if (!page)
+			break;
 		ion_page_pool_free_pages(pool, page);
 		freed += (1 << pool->order);
 	}
-- 
2.25.1