Re: a bug(BUG: kernel NULL pointer dereference) of ib or mlx happened in 5.4.21 but not in 5.4.20

[Maor Gottlieb <maorg@mellanox.com>]

On 2/20/2020 6:26 PM, Wang Yugui wrote:
> Hi, Leon, Chuck
>
> It is still broken even with the hotfix(https://patchwork.kernel.org/patch/11387567/) for 5.4.21.

Hi Wang,

How can I reproduce it ?

Can you please try with the below diff?

iff --git a/drivers/infiniband/core/security.c 
b/drivers/infiniband/core/security.c
index b9a36ea244d4..2d5608315dc8 100644
--- a/drivers/infiniband/core/security.c
+++ b/drivers/infiniband/core/security.c
@@ -340,11 +340,15 @@ static struct ib_ports_pkeys *get_new_pps(const 
struct ib_qp *qp,
                 return NULL;

         if (qp_attr_mask & IB_QP_PORT)
-           new_pps->main.port_num =
-                   (qp_pps) ? qp_pps->main.port_num : qp_attr->port_num;
+         new_pps->main.port_num = qp_attr->port_num;
+ else if (qp_pps)
+         new_pps->main.port_num = qp_pps->main.port_num;
+
         if (qp_attr_mask & IB_QP_PKEY_INDEX)
-           new_pps->main.pkey_index = (qp_pps) ? qp_pps->main.pkey_index :
- qp_attr->pkey_index;
+         new_pps->main.pkey_index = qp_attr->pkey_index;
+ else if (qp_pps)
+         new_pps->main.pkey_index = qp_pps->main.pkey_index;
+
         if ((qp_attr_mask & IB_QP_PKEY_INDEX) && (qp_attr_mask & 
IB_QP_PORT))
                 new_pps->main.state = IB_PORT_PKEY_VALID;

>
> the call stack is almost the same.
>
> Feb 20 23:49:53 T630 kernel: Call Trace:
> Feb 20 23:49:53 T630 kernel: port_pkey_list_insert+0x30/0x1a0 [ib_core]
> Feb 20 23:49:53 T630 kernel: ? kmem_cache_alloc_trace+0x219/0x230
> Feb 20 23:49:53 T630 kernel: ib_security_modify_qp+0x244/0x3b0 [ib_core]
> Feb 20 23:49:53 T630 kernel: _ib_modify_qp+0x1c0/0x3c0 [ib_core]
> Feb 20 23:49:53 T630 kernel: ? dma_pool_free+0x24/0xc0
> Feb 20 23:49:53 T630 kernel: ipoib_init_qp+0x77/0x190 [ib_ipoib]
> Feb 20 23:49:53 T630 kernel: ? __mlx4_ib_query_pkey+0xe7/0x110 [mlx4_ib]
> Feb 20 23:49:53 T630 kernel: ? ib_find_pkey+0x98/0xe0 [ib_core]
> Feb 20 23:49:53 T630 kernel: ipoib_ib_dev_open_default+0x1a/0x180 [ib_ipoib]
> Feb 20 23:49:53 T630 kernel: ipoib_ib_dev_open+0x66/0xa0 [ib_ipoib]
> Feb 20 23:49:53 T630 kernel: ipoib_open+0x44/0x110 [ib_ipoib]
> Feb 20 23:49:53 T630 kernel: __dev_open+0xcd/0x160
> Feb 20 23:49:53 T630 kernel: __dev_change_flags+0x1ad/0x220
> Feb 20 23:49:53 T630 kernel: ? __dev_notify_flags+0x95/0xf0
> Feb 20 23:49:53 T630 kernel: dev_change_flags+0x21/0x60
> Feb 20 23:49:53 T630 kernel: do_setlink+0x320/0xf00
> Feb 20 23:49:53 T630 kernel: ? __nla_validate_parse+0x51/0x840
> Feb 20 23:49:53 T630 kernel: ? xas_load+0x8/0x80
> Feb 20 23:49:53 T630 kernel: ? __update_load_avg_cfs_rq+0x1d5/0x2c0
> Feb 20 23:49:53 T630 kernel: ? cpumask_next+0x17/0x20
> Feb 20 23:49:53 T630 kernel: ? __snmp6_fill_stats64.isra.56+0x6b/0x110
> Feb 20 23:49:53 T630 kernel: ? __nla_validate_parse+0x51/0x840
> Feb 20 23:49:53 T630 kernel: __rtnl_newlink+0x53d/0x890
> Feb 20 23:49:53 T630 kernel: ? __nla_reserve+0x38/0x50
> Feb 20 23:49:53 T630 kernel: ? __nla_put+0xc/0x20
> Feb 20 23:49:53 T630 kernel: ? __nla_reserve+0x38/0x50
> Feb 20 23:49:53 T630 kernel: ? __nla_put+0xc/0x20
> Feb 20 23:49:53 T630 kernel: ? nla_put+0x2f/0x40
> Feb 20 23:49:53 T630 kernel: ? __nla_reserve+0x38/0x50
> Feb 20 23:49:53 T630 kernel: ? __nla_put+0xc/0x20
> Feb 20 23:49:53 T630 kernel: ? nla_put+0x2f/0x40
> Feb 20 23:49:53 T630 kernel: ? rt6_fill_node+0x2d4/0x850
> Feb 20 23:49:53 T630 kernel: ? _cond_resched+0x15/0x30
> Feb 20 23:49:53 T630 kernel: ? kmem_cache_alloc_trace+0x1c9/0x230
> Feb 20 23:49:53 T630 kernel: rtnl_newlink+0x43/0x60
> Feb 20 23:49:53 T630 kernel: rtnetlink_rcv_msg+0x2b1/0x360
> Feb 20 23:49:53 T630 kernel: ? __kmalloc_node_track_caller+0x241/0x300
> Feb 20 23:49:53 T630 kernel: ? _cond_resched+0x15/0x30
> Feb 20 23:49:53 T630 kernel: ? rtnl_calcit.isra.32+0x110/0x110
> Feb 20 23:49:53 T630 kernel: netlink_rcv_skb+0x49/0x110
> Feb 20 23:49:53 T630 kernel: netlink_unicast+0x191/0x220
> Feb 20 23:49:53 T630 kernel: netlink_sendmsg+0x21d/0x3f0
> Feb 20 23:49:53 T630 kernel: sock_sendmsg+0x5b/0x60
> Feb 20 23:49:53 T630 kernel: ____sys_sendmsg+0x1eb/0x260
> Feb 20 23:49:53 T630 kernel: ? copy_msghdr_from_user+0xdb/0x160
> Feb 20 23:49:53 T630 kernel: ___sys_sendmsg+0x7c/0xc0
> Feb 20 23:49:53 T630 kernel: ? do_filp_open+0xa7/0x100
> Feb 20 23:49:53 T630 kernel: ? netdev_run_todo+0x5e/0x290
> Feb 20 23:49:53 T630 kernel: ? list_lru_add+0xb7/0x1d0
> Feb 20 23:49:53 T630 kernel: __sys_sendmsg+0x57/0xa0
> Feb 20 23:49:53 T630 kernel: do_syscall_64+0x5b/0x180
> Feb 20 23:49:53 T630 kernel: entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
>
> This card have 2 port, and port 1 is set as InfiniBand, port 2
> is set as Ethernet.
>
> # ibstat
> CA 'mlx4_0'
>          CA type: MT4099
>          Number of ports: 2
>          Firmware version: 2.42.5000
>          Hardware version: 1
>          Node GUID: 0xe41d2d03007b4080
>          System image GUID: 0xe41d2d03007b4083
>          Port 1:
>                  State: Down
>                  Physical state: Polling
>                  Rate: 10
>                  Base lid: 0
>                  LMC: 0
>                  SM lid: 0
>                  Capability mask: 0x02594868
>                  Port GUID: 0xe41d2d03007b4081
>                  Link layer: InfiniBand
>          Port 2:
>                  State: Down
>                  Physical state: Disabled
>                  Rate: 40
>                  Base lid: 0
>                  LMC: 0
>                  SM lid: 0
>                  Capability mask: 0x00010000
>                  Port GUID: 0xe61d2dfffe7b4082
>                  Link layer: Ethernet
>
>
> Best Regards
> 王玉贵
> 2020/02/21
>
>> On Thu, Feb 20, 2020 at 08:57:29AM -0500, Chuck Lever wrote:
>>> Hello!
>>>
>>> Thanks for your bug report.
>>>
>>>
>>>> On Feb 19, 2020, at 10:22 PM, Wang Yugui <wangyugui@e16-tech.com> wrote:
>>>>
>>>> Hi, chuck.lever
>>>>
>>>> a bug(BUG: kernel NULL pointer dereference) of ib or mlx happened in 5.4.21 but not in 5.4.20.
>>>>
>>>> maybe some releationship to xprtrdma-fix-dma-scatter-gather-list-mapping-imbalance.patch
>>> I don't see an obvious connection to fix-dma-scatter-gather-list-mapping-imbalance.
>>> The backtrace below is through IPoIB code paths. Those have nothing to do with
>>> NFS/RDMA, which is the only ULP code that is changed by my commit.
>>>
>>>
>>>> maybe the info is useful.
>>> I'm copying linux-rdma for a bigger set of eyeballs.
>>>
>>> My knee-jerk recommendation is that if you have a reliable reproducer, try "git bisect"
>>> between .20 and .21 to nail down a specific commit where the BUG starts to occur.
>> No need to bisect, it is me who broke.
>> The fix is already accepted, but not yet merged.
>> https://patchwork.kernel.org/patch/11387567/
>>
>> Thanks
> --------------------------------------
> 北京京垓科技有限公司
> 王玉贵	wangyugui@e16-tech.com
> 电话：+86-136-71123776
>