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Subject[PATCH 01/10] ext4: Use rcu_barrier() on module unload.
Date
The ext4 module uses rcu_call() thus it should use rcu_barrier()on
module unload.

The kmem cache ext4_pspace_cachep is sometimes free'ed using
call_rcu() callbacks. Thus, we must wait for completion of call_rcu()
before doing kmem_cache_destroy().

I have difficult determining if no new call_rcu() callbacks can be envoked.
Would the maintainer please verify this?

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

fs/ext4/mballoc.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 519a0a6..e271a9e 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2902,8 +2902,10 @@ int __init init_ext4_mballoc(void)

void exit_ext4_mballoc(void)
{
- /* XXX: synchronize_rcu(); */
+ /* Wait for completion of call_rcu()'s on ext4_pspace_cachep */
+ rcu_barrier();
kmem_cache_destroy(ext4_pspace_cachep);
+
kmem_cache_destroy(ext4_ac_cachep);
kmem_cache_destroy(ext4_free_ext_cachep);
}


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