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Date: Tue, 4 Jun 2019 14:58:51 +0800
From: Yanjun Zhu <yanjun.zhu@...cle.com>
To: santosh.shilimkar@...cle.com, davem@...emloft.net,
netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
rds-devel@....oracle.com,
haakon.bugge@...cle.com >> Håkon Bugge
<haakon.bugge@...cle.com>
Subject: Re: [PATCH 1/1] net: rds: fix memory leak when unload rds_rdma
Hi, All
The steps to reproduce this problem. And it is easy to reproduce.
1. boot with 5.2.0-rc2+, and KASAN is also enabled in this kernel
2. run the following scripts:
"
for i in `seq 0 5`
do
rds-ping -c 2 1.1.1.14 -Q $i
done
"
3. run "rmmod rds_rdma"
4. check /var/log/dmesg, the following will appear.
"
BUG rds_ib_incoming (Tainted: G OE ): Objects remaining in
rds_ib_incoming on __kmem_cache_shutdown()
-----------------------------------------------------------------------------
Disabling lock debugging due to kernel taint
INFO: Slab 0x00000000e0306204 objects=32 used=1 fp=0x0000000050936906
flags=0x17fffc000010200
CPU: 20 PID: 6643 Comm: rmmod Tainted: G B OE 5.2.0-rc2+ #1
Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER
/ASSY,MOTHERBOARD,X4170, BIOS 08140112 08/03/2016
Call Trace:
dump_stack+0x71/0xab
slab_err+0xad/0xd0
? __kasan_kmalloc+0xd5/0xf0
? kasan_unpoison_shadow+0x31/0x40
__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
RIP: 0033:0x7f424d53b457
Code: 73 01 c3 48 8b 0d 19 7a 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e
0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00 00 0f 05 <48> 3d 01
f0 ff ff 73 01 c3 48 8b 0d e9 79 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe70e8f048 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000000001bc1210 RCX: 00007f424d53b457
RDX: 00007f424d5afbe0 RSI: 0000000000000800 RDI: 0000000001bc1278
RBP: 0000000000000000 R08: 00007f424d804060 R09: 00007f424d5afbe0
R10: 00007ffe70e8ec10 R11: 0000000000000206 R12: 00007ffe70e90879
R13: 0000000000000000 R14: 0000000001bc1210 R15: 0000000001bc1010
INFO: Object 0x000000003c6e3538 @offset=0
kmem_cache_destroy rds_ib_incoming: Slab cache still has objects
CPU: 20 PID: 6643 Comm: rmmod Tainted: G B OE 5.2.0-rc2+ #1
Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER
/ASSY,MOTHERBOARD,X4170, BIOS 08140112 08/03/2016
Call Trace:
dump_stack+0x71/0xab
kmem_cache_destroy+0x1fd/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
RIP: 0033:0x7f424d53b457
Code: 73 01 c3 48 8b 0d 19 7a 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e
0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00 00 0f 05 <48> 3d 01
f0 ff ff 73 01 c3 48 8b 0d e9 79 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe70e8f048 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000000001bc1210 RCX: 00007f424d53b457
RDX: 00007f424d5afbe0 RSI: 0000000000000800 RDI: 0000000001bc1278
RBP: 0000000000000000 R08: 00007f424d804060 R09: 00007f424d5afbe0
R10: 00007ffe70e8ec10 R11: 0000000000000206 R12: 00007ffe70e90879
R13: 0000000000000000 R14: 0000000001bc1210 R15: 0000000001bc1010
=============================================================================
BUG rds_ib_frag (Tainted: G B OE ): Objects remaining in
rds_ib_frag on __kmem_cache_shutdown()
-----------------------------------------------------------------------------
INFO: Slab 0x00000000b70dee4a objects=32 used=1 fp=0x000000001dde4640
flags=0x17fffc000000200
CPU: 21 PID: 6643 Comm: rmmod Tainted: G B OE 5.2.0-rc2+ #1
Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER
/ASSY,MOTHERBOARD,X4170, BIOS 08140112 08/03/2016
Call Trace:
dump_stack+0x71/0xab
slab_err+0xad/0xd0
? __kasan_kmalloc+0xd5/0xf0
? kasan_unpoison_shadow+0x31/0x40
__kmem_cache_shutdown+0x17d/0x370
shutdown_cache+0x17/0x130
kmem_cache_destroy+0x1df/0x210
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
RIP: 0033:0x7f424d53b457
Code: 73 01 c3 48 8b 0d 19 7a 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e
0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00 00 0f 05 <48> 3d 01
f0 ff ff 73 01 c3 48 8b 0d e9 79 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe70e8f048 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000000001bc1210 RCX: 00007f424d53b457
RDX: 00007f424d5afbe0 RSI: 0000000000000800 RDI: 0000000001bc1278
RBP: 0000000000000000 R08: 00007f424d804060 R09: 00007f424d5afbe0
R10: 00007ffe70e8ec10 R11: 0000000000000206 R12: 00007ffe70e90879
R13: 0000000000000000 R14: 0000000001bc1210 R15: 0000000001bc1010
INFO: Object 0x000000001d5f42ef @offset=0
kmem_cache_destroy rds_ib_frag: Slab cache still has objects
CPU: 21 PID: 6643 Comm: rmmod Tainted: G B OE 5.2.0-rc2+ #1
Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER
/ASSY,MOTHERBOARD,X4170, BIOS 08140112 08/03/2016
Call Trace:
dump_stack+0x71/0xab
kmem_cache_destroy+0x1fd/0x210
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
RIP: 0033:0x7f424d53b457
Code: 73 01 c3 48 8b 0d 19 7a 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e
0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00 00 0f 05 <48> 3d 01
f0 ff ff 73 01 c3 48 8b 0d e9 79 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe70e8f048 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000000001bc1210 RCX: 00007f424d53b457
RDX: 00007f424d5afbe0 RSI: 0000000000000800 RDI: 0000000001bc1278
RBP: 0000000000000000 R08: 00007f424d804060 R09: 00007f424d5afbe0
R10: 00007ffe70e8ec10 R11: 0000000000000206 R12: 00007ffe70e90879
R13: 0000000000000000 R14: 0000000001bc1210 R15: 0000000001bc1010
Unregistered RDS/infiniband transport
"
5. after this commit is applied. Repeat the above steps. Check
/var/log/dmesg,
only the following appear.
"
[101287.926043] Unregistered RDS/infiniband transport
"
So IMO, this commit fixes this problem. The root cause is in the commit log.
Zhu Yanjun
On 2019/6/3 20:43, Yanjun Zhu wrote:
> Sorry. Add Håkon Bugge <haakon.bugge@...cle.com>
>
> He told me to notice the memory leak when caches are freed.
>
> Zhu Yanjun
>
> On 2019/6/3 20:48, Zhu Yanjun wrote:
>> 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@...dev14 ~]# time rmmod rds_rdma
>>
>> real 0m16.522s
>> user 0m0.000s
>> sys 0m8.152s
>> 512 rds connections
>> [root@...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: Håkon Bugge <haakon.bugge@...cle.com>
>> Signed-off-by: Zhu Yanjun <yanjun.zhu@...cle.com>
>> ---
>> net/rds/ib.c | 2 +-
>> net/rds/ib_recv.c | 3 +++
>> 2 files changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/rds/ib.c b/net/rds/ib.c
>> index f9baf2d..ec05d91 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 8946c89..3cae88c 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 @@ int rds_ib_recv_init(void)
>> 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);
>> }
>
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