[PATCH 6/6] mm/zpool: prevent zbud/zsmalloc from unloading when used

[Dan Streetman]

Add try_module_get() to pool creation functions for zbud and zsmalloc,
and module_put() to pool destruction functions, since they now can be
modules used via zpool.  Without usage counting, they could be unloaded
while pool(s) were active, resulting in an oops.

Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
Cc: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Weijie Yang <weijie.yang@xxxxxxxxxxx>
---

New for this patch set.

 mm/zbud.c     | 5 +++++
 mm/zsmalloc.c | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/mm/zbud.c b/mm/zbud.c
index 8a72cb1..2b3689c 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -282,6 +282,10 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops)
 	pool = kmalloc(sizeof(struct zbud_pool), GFP_KERNEL);
 	if (!pool)
 		return NULL;
+	if (!try_module_get(THIS_MODULE)) {
+		kfree(pool);
+		return NULL;
+	}
 	spin_lock_init(&pool->lock);
 	for_each_unbuddied_list(i, 0)
 		INIT_LIST_HEAD(&pool->unbuddied[i]);
@@ -302,6 +306,7 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops)
 void zbud_destroy_pool(struct zbud_pool *pool)
 {
 	kfree(pool);
+	module_put(THIS_MODULE);
 }
 
 /**
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 07c3130..2cc2647 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -946,6 +946,10 @@ struct zs_pool *zs_create_pool(gfp_t flags)
 	pool = kzalloc(ovhd_size, GFP_KERNEL);
 	if (!pool)
 		return NULL;
+	if (!try_module_get(THIS_MODULE)) {
+		kfree(pool);
+		return NULL;
+	}
 
 	for (i = 0; i < ZS_SIZE_CLASSES; i++) {
 		int size;
@@ -985,6 +989,7 @@ void zs_destroy_pool(struct zs_pool *pool)
 		}
 	}
 	kfree(pool);
+	module_put(THIS_MODULE);
 }
 EXPORT_SYMBOL_GPL(zs_destroy_pool);
 
-- 
1.8.3.1

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