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authorZhu Yanjun <yanjun.zhu@oracle.com>2019-06-03 15:48:19 +0300
committerDavid S. Miller <davem@davemloft.net>2019-06-06 03:08:14 +0300
commitb50e058746ba29f517e27299447831ab3d93f896 (patch)
tree58b46492f5e05d75ef0d4f3abe09712359c36dfb /net/rds
parentb7999b07726c16974ba9ca3bb9fe98ecbec5f81c (diff)
downloadlinux-b50e058746ba29f517e27299447831ab3d93f896.tar.xz
net: rds: fix memory leak when unload rds_rdma
When KASAN is enabled, after several rds connections are created, then "rmmod rds_rdma" is run. The following will appear. " BUG rds_ib_incoming (Not tainted): Objects remaining in rds_ib_incoming on __kmem_cache_shutdown() Call Trace: dump_stack+0x71/0xab slab_err+0xad/0xd0 __kmem_cache_shutdown+0x17d/0x370 shutdown_cache+0x17/0x130 kmem_cache_destroy+0x1df/0x210 rds_ib_recv_exit+0x11/0x20 [rds_rdma] rds_ib_exit+0x7a/0x90 [rds_rdma] __x64_sys_delete_module+0x224/0x2c0 ? __ia32_sys_delete_module+0x2c0/0x2c0 do_syscall_64+0x73/0x190 entry_SYSCALL_64_after_hwframe+0x44/0xa9 " This is rds connection memory leak. The root cause is: When "rmmod rds_rdma" is run, rds_ib_remove_one will call rds_ib_dev_shutdown to drop the rds connections. rds_ib_dev_shutdown will call rds_conn_drop to drop rds connections as below. " rds_conn_path_drop(&conn->c_path[0], false); " In the above, destroy is set to false. void rds_conn_path_drop(struct rds_conn_path *cp, bool destroy) { atomic_set(&cp->cp_state, RDS_CONN_ERROR); rcu_read_lock(); if (!destroy && rds_destroy_pending(cp->cp_conn)) { rcu_read_unlock(); return; } queue_work(rds_wq, &cp->cp_down_w); rcu_read_unlock(); } In the above function, destroy is set to false. rds_destroy_pending is called. This does not move rds connections to ib_nodev_conns. So destroy is set to true to move rds connections to ib_nodev_conns. In rds_ib_unregister_client, flush_workqueue is called to make rds_wq finsh shutdown rds connections. The function rds_ib_destroy_nodev_conns is called to shutdown rds connections finally. Then rds_ib_recv_exit is called to destroy slab. void rds_ib_recv_exit(void) { kmem_cache_destroy(rds_ib_incoming_slab); kmem_cache_destroy(rds_ib_frag_slab); } The above slab memory leak will not occur again. >From tests, 256 rds connections [root@ca-dev14 ~]# time rmmod rds_rdma real 0m16.522s user 0m0.000s sys 0m8.152s 512 rds connections [root@ca-dev14 ~]# time rmmod rds_rdma real 0m32.054s user 0m0.000s sys 0m15.568s To rmmod rds_rdma with 256 rds connections, about 16 seconds are needed. And with 512 rds connections, about 32 seconds are needed. >From ftrace, when one rds connection is destroyed, " 19) | rds_conn_destroy [rds]() { 19) 7.782 us | rds_conn_path_drop [rds](); 15) | rds_shutdown_worker [rds]() { 15) | rds_conn_shutdown [rds]() { 15) 1.651 us | rds_send_path_reset [rds](); 15) 7.195 us | } 15) + 11.434 us | } 19) 2.285 us | rds_cong_remove_conn [rds](); 19) * 24062.76 us | } " So if many rds connections will be destroyed, this function rds_ib_destroy_nodev_conns uses most of time. Suggested-by: HÃ¥kon Bugge <haakon.bugge@oracle.com> Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds')
-rw-r--r--net/rds/ib.c2
-rw-r--r--net/rds/ib_recv.c3
2 files changed, 4 insertions, 1 deletions
diff --git a/net/rds/ib.c b/net/rds/ib.c
index 2da9b75bad16..b8d581b779b2 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -87,7 +87,7 @@ static void rds_ib_dev_shutdown(struct rds_ib_device *rds_ibdev)
spin_lock_irqsave(&rds_ibdev->spinlock, flags);
list_for_each_entry(ic, &rds_ibdev->conn_list, ib_node)
- rds_conn_drop(ic->conn);
+ rds_conn_path_drop(&ic->conn->c_path[0], true);
spin_unlock_irqrestore(&rds_ibdev->spinlock, flags);
}
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 8946c89d7392..3cae88cbdaa0 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -168,6 +168,7 @@ void rds_ib_recv_free_caches(struct rds_ib_connection *ic)
list_del(&inc->ii_cache_entry);
WARN_ON(!list_empty(&inc->ii_frags));
kmem_cache_free(rds_ib_incoming_slab, inc);
+ atomic_dec(&rds_ib_allocation);
}
rds_ib_cache_xfer_to_ready(&ic->i_cache_frags);
@@ -1057,6 +1058,8 @@ out:
void rds_ib_recv_exit(void)
{
+ WARN_ON(atomic_read(&rds_ib_allocation));
+
kmem_cache_destroy(rds_ib_incoming_slab);
kmem_cache_destroy(rds_ib_frag_slab);
}