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Subject[PATCH 6/6] mm/zpool: prevent zbud/zsmalloc from unloading when used
Date
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@ieee.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Weijie Yang <weijie.yang@samsung.com>
---

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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