Re: [PATCH V1] NFS-RDMA: fix qp pointer validation checks

[Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

Hi Devesh-

On Apr 10, 2014, at 1:54 PM, Devesh Sharma <Devesh.Sharma-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org> wrote:

> Alright here it is:
> 
> <3>ocrdma_mbx_create_qp(0) rq_err
> <3>ocrdma_mbx_create_qp(0) sq_err
> <3>ocrdma_create_qp(0) error=-1
> <1>BUG: unable to handle kernel NULL pointer dereference at (null)
> <1>IP: [<ffffffffa078e8ac>] rpcrdma_deregister_frmr_external+0x9c/0xe0 [xprtrdma]

As near as I can ascertain, the RDMA connection is torn down while an NFS workload is running, and a new connection cannot be completely set up.

Can you try this:

 1. On your client, # rpcdebug -m rpc -s call xprt sched trans

 2. Reproduce the failure

 3. Post the relevant contents of /var/log/messages (like the last RPC request or two before the BUG)

And post the relevant line in /proc/mounts corresponding to your test NFS/RDMA mount.


> <4>PGD 455942067 PUD 458356067 PMD 0
> <4>Oops: 0000 [#1] SMP
> <4>last sysfs file: /sys/devices/pci0000:80/0000:80:03.0/0000:8b:00.1/class
> <4>CPU 1
> <4>Modules linked in: nfs fscache xprtrdma(U) ocrdma(U) fuse ip6table_filter ip6_tables ebtable_nat ebtables ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack ipt_REJECT xt_CHECKSUM iptable_mangle iptable_filter ip_tables bridge nfsd lockd nfs_acl auth_rpcgss exportfs autofs4 sunrpc target_core_iblock target_core_file target_core_pscsi target_core_mod configfs bnx2fc cnic uio fcoe libfcoe 8021q garp libfc stp llc rdma_ucm(U) rdma_cm(U) iw_cm(U) ib_addr(U) ib_ipoib(U) ib_cm(U) ib_sa(U) ipv6 ib_uverbs(U) ib_umad(U) iw_nes(U) libcrc32c iw_cxgb4(U) cxgb4(U) iw_cxgb3(U) cxgb3(U) mdio ib_qib(U) mlx4_en(U) mlx4_ib(U) mlx4_core(U) ib_mthca(U) ib_mad(U) ib_core(U) compat(U) vfat fat vhost_net macvtap macvlan tun kvm_intel kvm uinput sg cdc_ether usbnet mii m
 icrocode i2c_i801 i2c_core iTCO_wdt iTCO_vendor_support shpchp igb ptp pps_core ioatdma dca be2net(U) ext4 mbcache jbd2 sr_mod cdrom sd_mod crc_t10dif lpfc scsi_transport_fc scsi_tgt ahci wmi megaraid_sas dm_mirror dm_region_hash dm_log dm_mod [last unloaded: speedstep_lib]
> <4>
> <4>Pid: 9204, comm: ls Not tainted 2.6.32-358.el6.x86_64 #1 IBM System x3650 M4 -[7915AC1]-/00J6528
> <4>RIP: 0010:[<ffffffffa078e8ac>]  [<ffffffffa078e8ac>] rpcrdma_deregister_frmr_external+0x9c/0xe0 [xprtrdma]
> <4>RSP: 0018:ffff8804551877f8  EFLAGS: 00010217
> <4>RAX: ffff880462243800 RBX: ffff88045646a028 RCX: 0000000000000000
> <4>RDX: ffff880455187860 RSI: ffff8804551877f8 RDI: 0000000000000000
> <4>RBP: ffff880455187888 R08: 0000000000000000 R09: 0000000000000000
> <4>R10: 0000000000000000 R11: 0000000000000000 R12: ffff88047601c598
> <4>R13: ffff88047601c000 R14: ffff88045646a068 R15: 0000000000000000
> <4>FS:  00007fd669be07a0(0000) GS:ffff880028220000(0000) knlGS:0000000000000000
> <4>CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> <4>CR2: 0000000000000000 CR3: 00000004557de000 CR4: 00000000000407e0
> <4>DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> <4>DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> <4>Process ls (pid: 9204, threadinfo ffff880455186000, task ffff880456735540)
> <4>Stack:
> <4> 0000000000000000 ffff88045584a700 0000000000000000 0000000a00000000
> <4><d> 080424b400000002 0000000000000000 0000000000000000 0000000000000000
> <4><d> 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> <4>Call Trace:
> <4> [<ffffffffa078ea03>] rpcrdma_deregister_external+0x113/0x2d0 [xprtrdma]
> <4> [<ffffffffa078c4fc>] xprt_rdma_free+0x8c/0x210 [xprtrdma]
> <4> [<ffffffff81082014>] ? mod_timer+0x144/0x220
> <4> [<ffffffffa07bba60>] xprt_release+0xc0/0x220 [sunrpc]
> <4> [<ffffffffa07c2f5d>] rpc_release_resources_task+0x1d/0x50 [sunrpc]
> <4> [<ffffffffa07c3a84>] __rpc_execute+0x174/0x350 [sunrpc]
> <4> [<ffffffff81096b47>] ? bit_waitqueue+0x17/0xd0
> <4> [<ffffffffa07c3cc1>] rpc_execute+0x61/0xa0 [sunrpc]
> <4> [<ffffffffa07ba3a5>] rpc_run_task+0x75/0x90 [sunrpc]
> <4> [<ffffffffa07ba4c2>] rpc_call_sync+0x42/0x70 [sunrpc]
> <4> [<ffffffffa08b6f6d>] nfs3_rpc_wrapper.clone.0+0x3d/0xd0 [nfs]
> <4> [<ffffffffa08b734c>] nfs3_proc_access+0xbc/0x180 [nfs]
> <4> [<ffffffffa089f1e9>] nfs_do_access+0x199/0x3c0 [nfs]
> <4> [<ffffffffa07c6305>] ? generic_lookup_cred+0x15/0x20 [sunrpc]
> <4> [<ffffffffa07c52e0>] ? rpcauth_lookupcred+0x70/0xc0 [sunrpc]
> <4> [<ffffffffa089f4b8>] nfs_permission+0xa8/0x1e0 [nfs]
> <4> [<ffffffff8119053d>] __link_path_walk+0xad/0x1030
> <4> [<ffffffff81143a17>] ? handle_pte_fault+0x487/0xb50
> <4> [<ffffffff8132b1fa>] ? copy_termios+0x6a/0x80
> <4> [<ffffffff8119174a>] path_walk+0x6a/0xe0
> <4> [<ffffffff8119191b>] do_path_lookup+0x5b/0xa0
> <4> [<ffffffff811925a7>] user_path_at+0x57/0xa0
> <4> [<ffffffff81194ed2>] ? vfs_ioctl+0x22/0xa0
> <4> [<ffffffff811869bc>] vfs_fstatat+0x3c/0x80
> <4> [<ffffffff81085151>] ? do_sigaction+0x91/0x1d0
> <4> [<ffffffff81186b2b>] vfs_stat+0x1b/0x20
> <4> [<ffffffff81186b54>] sys_newstat+0x24/0x50
> <4> [<ffffffff8151311e>] ? do_page_fault+0x3e/0xa0
> <4> [<ffffffff815104d5>] ? page_fault+0x25/0x30
> <4> [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
> <4>Code: 48 89 85 78 ff ff ff 48 8b 40 08 8b 40 1c 89 45 94 b8 ff ff ff ff f0 41 0f c1 85 e0 05 00 00 49 8b 04 24 48 8d 55 d8 48 8b 78 10 <48> 8b 07 ff 90 b0 01 00 00 85 c0 89 c3 74 09 80 3d 56 8d 05 00
> <1>RIP  [<ffffffffa078e8ac>] rpcrdma_deregister_frmr_external+0x9c/0xe0 [xprtrdma]
> <4> RSP <ffff8804551877f8>
> <4>CR2: 0000000000000000
> 
>> -----Original Message-----
>> From: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [mailto:linux-rdma-
>> owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org] On Behalf Of Chuck Lever
>> Sent: Thursday, April 10, 2014 11:21 PM
>> To: Devesh Sharma
>> Cc: Linux NFS Mailing List; linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Trond Myklebust
>> Subject: Re: [PATCH V1] NFS-RDMA: fix qp pointer validation checks
>> 
>> 
>> On Apr 10, 2014, at 1:42 PM, Devesh Sharma
>> <Devesh.Sharma-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org> wrote:
>> 
>>>> However it seems to me the new (!ia->ri_id->qp) checks outside the
>>>> connect logic are unnecessary.
>>>> 
>>>> Clearly, as you noticed, the ib_post_{send,recv} verbs do not check
>>>> that their "qp" argument is NULL before dereferencing it.
>>>> 
>>>> But I don't understand how xprtrdma can post any operation if the
>>>> transport isn't connected. In other words, how would it be possible
>>>> to call
>>>> rpcrdma_ep_post_recv() if the connect had failed and there was no QP?
>>>> 
>>>> If disconnect wipes ia->ri_id->qp while there are still operations in
>>>> progress, that would be the real bug.
>>> Yes!, But I have seen one more kernel oops where QP is destroyed and
>>> xprtrdma still try to post in LOCAL_INV WR on a NULL QP pointer and hence
>> system crashes. So, I think what you missioned is really happening.
>> 
>> I'd like to see the crash data (back trace, etc), if you've got it.
>> 
>> --
>> Chuck Lever
>> chuck[dot]lever[at]oracle[dot]com
>> 
>> 
>> 
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the
>> body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at
>> http://vger.kernel.org/majordomo-info.html

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com



--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html