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Subject: Re: Soft lockup in unloading kernel modules
From: Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <53724CF1.8030509@ims.co.at>
Date: Mon, 19 May 2014 13:51:42 -0400
Cc: linux-rdma <linux-rdma@vger.kernel.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Message-Id: <B8C78BF6-A287-4409-A504-76670A68C9A2@oracle.com>
References: <lkg4ae$hj7$1@ger.gmane.org> <536BA9DE.2060702@gmail.com> <53724CF1.8030509@ims.co.at>
To: Klemens Senn <klemens.senn@ims.co.at>
Sender: linux-nfs-owner@vger.kernel.org
List-ID: <linux-nfs.vger.kernel.org>

Hi Klemens-

On May 13, 2014, at 12:48 PM, Klemens Senn <klemens.senn@ims.co.at> wrote:

> Hi Anna,
> 
> today I retried unloading the kernel modules with your updated kernel
> and additionally I tried the nfsd-next kernel from J. Bruce Fields and
> Chuck's nfs-rdma-client kernel.

I filed

  https://bugzilla.linux-nfs.org/show_bug.cgi?id=252

to track this issue.


> In short: None of these was able to unload the kernel modules with an
> active connection.
> 
> In detail:
> 
> With your kernel I got following 3 faults:
>  o BUG: soft lockup - CPU#0 stuck for 22s! [modprobe:4615]
>  o BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000003
>  o BUG: unable to handle kernel paging request at 0000000000005b8c
> 
> With the nfsd-next kernel I got following results:
>  o BUG: soft lockup - CPU#0 stuck for 23s! [modprobe:4452]
>  o module unloading blocks forever, dmesg shows:
>    nfsd: last server has exited, flushing export cache
>    waiting module removal not supported: please upgrade
>  o Kernel keeps running but reports the following:
>    nfsd: last server has exited, flushing export cache
>    waiting module removal not supported: please upgrade
>    svc_xprt_enqueue: threads and transports both waiting??
>    INFO: task modprobe:4510 blocked for more than 480 seconds.
>          Not tainted 3.15.0-rc1-bfields-master+ #1
>    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
> message.
>    modprobe        D ffff88087fc13440     0  4510   4458 0x00000000
>     ffff88105bb23c58 0000000000000086 ffff88105c14e690 0000000000013440
>     ffff88105bb23fd8 0000000000013440 ffffffff81a14480 ffff88105c14e690
>     0000000000000037 ffff88085d7f74d8 ffff88085d7f74e0 7fffffffffffffff
>    Call Trace:
>     [<ffffffff815a2424>] schedule+0x24/0x70
>     [<ffffffff815a18cc>] schedule_timeout+0x1ec/0x260
>     [<ffffffff8159a504>] ? printk+0x5c/0x5e
>     [<ffffffff815a3406>] wait_for_completion+0x96/0x100
>     [<ffffffff81080c90>] ? try_to_wake_up+0x2b0/0x2b0
>     [<ffffffffa0314039>] cma_remove_one+0x1a9/0x220 [rdma_cm]
>     [<ffffffffa01fea86>] ib_unregister_device+0x46/0x120 [ib_core]
>     [<ffffffffa02c5dc9>] mlx4_ib_remove+0x29/0x260 [mlx4_ib]
>     [<ffffffffa04319d0>] mlx4_remove_device+0xa0/0xc0 [mlx4_core]
>     [<ffffffffa0431a2b>] mlx4_unregister_interface+0x3b/0xa0 [mlx4_core]
>     [<ffffffffa02d74cc>] mlx4_ib_cleanup+0x10/0x23 [mlx4_ib]
>     [<ffffffff810bd612>] SyS_delete_module+0x152/0x220
>     [<ffffffff81149684>] ? vm_munmap+0x54/0x70
>     [<ffffffff815ad5a6>] system_call_fastpath+0x1a/0x1f
> 
> With the nfs-rdma-client I got following results:
>  o module unloading blocks forever, dmesg shows:
>    nfsd: last server has exited, flushing export cache
>    svc_xprt_enqueue: threads and transports both waiting??
>  o BUG: unable to handle kernel paging request at 0000000000004dec
>    IP: [<ffffffff815a63b5>] _raw_spin_lock_bh+0x15/0x40
>    PGD 107ba9a067 PUD 105c093067 PMD 0
>    Oops: 0002 [#1] SMP
>    Modules linked in: nfsd nfs_acl auth_rpcgss oid_registry svcrdma
> dm_mod cpuid nfs fscache lockd sunrpc af_packet 8021q garp stp llc
> rdma_ucm ib_ucm rdma_cm iw_cm ib_ipoib ib_cm ib_uverbs ib_umad mlx4_en
> mlx4_ib(-) ib_sa ib_mad ib_core ib_addr sr_mod cdrom usb_storage joydev
> mlx4_core usbhid x86_pkg_temp_thermal coretemp kvm_intel kvm
> ghash_clmulni_intel aesni_intel ablk_helper cryptd lrw gf128mul
> glue_helper ehci_pci aes_x86_64 ehci_hcd isci iTCO_wdt libsas pcspkr
> iTCO_vendor_support igb i2c_algo_bit sb_edac lpc_ich edac_core ioatdma
> usbcore tpm_tis ptp microcode i2c_i801 sg mfd_core scsi_transport_sas
> ipmi_si usb_common tpm wmi pps_core dca ipmi_msghandler acpi_cpufreq
> button edd autofs4 xfs libcrc32c crc32c_intel processor thermal_sys
> scsi_dh_rdac scsi_dh_hp_sw scsi_dh_emc scsi_dh_alua scsi_dh
>    CPU: 14 PID: 4813 Comm: modprobe Not tainted
> 3.15.0-rc5-cel-nfs-rdma-client-unpatched+ #2
>    Hardware name: Supermicro B9DRG-E/B9DRG-E, BIOS 3.0 09/04/2013
>    task: ffff88085bf96190 ti: ffff88085d42a000 task.ti: ffff88085d42a000
>    RIP: 0010:[<ffffffff815a63b5>]  [<ffffffff815a63b5>]
> _raw_spin_lock_bh+0x15/0x40
>    RSP: 0018:ffff88085d42bd18  EFLAGS: 00010286
>    RAX: 0000000000010000 RBX: 0000000000004de8 RCX: 0000000000000000
>    RDX: 000000000000000b RSI: 000000000000000e RDI: 0000000000004dec
>    RBP: ffff88085d42bd18 R08: ffff88087c611f38 R09: 000000000000a140
>    R10: 000000000000002b R11: 0000000000000000 R12: ffff88085dcc3c00
>    R13: ffff88105ca13280 R14: 0000000000004dec R15: 0000000000004df0
>    FS:  00007f0e49fb5700(0000) GS:ffff88107fcc0000(0000)
> knlGS:0000000000000000
>    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>    CR2: 0000000000004dec CR3: 000000105b027000 CR4: 00000000000407e0
>    Stack:
>     ffff88085d42bd58 ffffffffa03bd9f0 0000000001328b88 ffff88085dcc3c00
>     ffff88085dce8000 ffff88105ca13280 ffff88085dce8260 ffff88085dce81c8
>     ffff88085d42bd78 ffffffffa0441ce9 ffff88085dce8000 ffff88105ca13240
>    Call Trace:
>     [<ffffffffa03bd9f0>] svc_xprt_enqueue+0x50/0x220 [sunrpc]
>     [<ffffffffa0441ce9>] rdma_cma_handler+0x69/0x180 [svcrdma]
>     [<ffffffffa031a086>] cma_remove_one+0x1f6/0x220 [rdma_cm]
>     [<ffffffffa0261a86>] ib_unregister_device+0x46/0x120 [ib_core]
>     [<ffffffffa02b9dc9>] mlx4_ib_remove+0x29/0x260 [mlx4_ib]
>     [<ffffffffa02329d0>] mlx4_remove_device+0xa0/0xc0 [mlx4_core]
>     [<ffffffffa0232a2b>] mlx4_unregister_interface+0x3b/0xa0 [mlx4_core]
>     [<ffffffffa02cb4cc>] mlx4_ib_cleanup+0x10/0x23 [mlx4_ib]
>     [<ffffffff810bd6f0>] SyS_delete_module+0x170/0x1f0
>     [<ffffffff811497f4>] ? vm_munmap+0x54/0x70
>     [<ffffffff815ae426>] system_call_fastpath+0x1a/0x1f
>    Code: 5d c3 0f b7 17 66 39 ca 74 f6 f3 90 0f b7 17 66 39 d1 75 f6 5d
> c3 55 65 81 04 25 20 b9 00 00 00 02 00 00 48 89 e5 b8 00 00 01 00 <f0>
> 0f c1 07 89 c2 c1 ea 10 66 39 c2 75 04 5d c3 f3 90 0f b7 07
>    RIP  [<ffffffff815a63b5>] _raw_spin_lock_bh+0x15/0x40
>     RSP <ffff88085d42bd18>
>    CR2: 0000000000004dec
>    ---[ end trace bf1fd548a33cbfc4 ]---
>    Kernel panic - not syncing: Fatal exception in interrupt
>    Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range:
> 0xffffffff80000000-0xffffffff9fffffff)
>    ---[ end Kernel panic - not syncing: Fatal exception in interrupt
> 
> 
> Regards,
> Klemens
> 
> 
> On 05/08/2014 05:59 PM, Anna Schumaker wrote:
>> I haven't applied Chuck's recent (v3) patches to that kernel yet (I've been waiting to see if people have comments).  I'll try to push something out today.
>> 
>> On 05/08/2014 10:28 AM, Senn Klemens wrote:
>>> Hi,
>>> 
>>> I am getting a soft lockup on the NFS server on its reboot if at least
>>> one client mount is established. I am using OpenSUSE 12.3 with the
>>> nfs-rdma kernel from Anna Schumaker
>>> (git://git.linux-nfs.org/projects/anna/nfs-rdma.git).
>>> 
>>> The export on the server side is done with
>>> /data	*(fsid=0,crossmnt,rw,mp,no_root_squash,sync,no_subtree_check,insecure)
>>> 
>>> Following command is used for mounting the NFSv4 share:
>>> mount -t nfs -o port=20049,rdma,vers=4.0,timeo=900 172.16.100.19:/ /mnt
>>> 
>>> The HCA is a Mellanox MT4099 on the server and the client.
>>> 
>>> The soft lockup can be reproduced by following steps:
>>>  o server: Start the nfs server
>>>  o client: Mount the share
>>>  o client: Do a "ls" in the mounted directory
>>>  o server: Stop the nfs server
>>>  o server: Unload the nfs and mlx4 modules or reboot the server (I used
>>> the openibd init script from the Mellanox driver without having the
>>> Mellanox stack installed)
>>> 
>>> The server reports a soft lockup
>>>  BUG: soft lockup - CPU#0 stuck for 22s! [modprobe:6146]
>>> most times.
>>> 
>>> Sometimes I get following kernel panic
>>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000003
>>> IP: [<ffffffff815a5c35>] _raw_spin_lock_bh+0x15/0x40
>>> PGD 82a820067 PUD 857832067 PMD 0
>>> Oops: 0002 [#1] SMP
>>> Modules linked in: nfsd nfs_acl auth_rpcgss oid_registry nfnetlink_log
>>> nfnetlink bluetooth rfkill nfsv4 svcrdma dm_mod cpuid nfs fscache lockd
>>> sunrpc af_packet 8021q garp stp llc rdma_ucm ib_ucm rdma_cm iw_cm
>>> ib_ipoib ib_cm ib_uverbs ib_umad mlx4_en mlx4_ib(-) ib_sa ib_mad ib_core
>>> ib_addr sr_mod cdrom usb_storage joydev mlx4_core usbhid
>>> x86_pkg_temp_thermal coretemp kvm_intel kvm ghash_clmulni_intel
>>> aesni_intel ablk_helper cryptd iTCO_wdt lrw igb gf128mul
>>> iTCO_vendor_support ehci_pci glue_helper pcspkr i2c_algo_bit isci
>>> ehci_hcd aes_x86_64 ptp libsas ioatdma lpc_ich microcode sb_edac sg
>>> pps_core usbcore ipmi_si tpm_tis edac_core scsi_transport_sas i2c_i801
>>> mfd_core dca usb_common tpm ipmi_msghandler wmi acpi_cpufreq button edd
>>> autofs4 xfs libcrc32c crc32c_intel processor thermal_sys scsi_dh_rdac
>>> scsi_dh_hp_sw scsi_dh_emc scsi_dh_alua scsi_dh [last unloaded: oid_registry]
>>> CPU: 0 PID: 6603 Comm: modprobe Not tainted 3.15.0-rc2-anna-nfs-rdma+ #3
>>> Hardware name: Supermicro B9DRG-E/B9DRG-E, BIOS 3.0 09/04/2013
>>> task: ffff88105b8c6050 ti: ffff88105d814000 task.ti: ffff88105d814000
>>> RIP: 0010:[<ffffffff815a5c35>]  [<ffffffff815a5c35>]
>>> _raw_spin_lock_bh+0x15/0x40
>>> RSP: 0018:ffff88105d815d18  EFLAGS: 00010286
>>> RAX: 0000000000010000 RBX: ffffffffffffffff RCX: 0000000000000000
>>> RDX: 000000000000000b RSI: 0000000000000000 RDI: 0000000000000003
>>> RBP: ffff88105d815d18 R08: ffff88087c611f38 R09: 0000000000000001
>>> R10: 0000000000000000 R11: 0000000000000000 R12: ffff88087c3c9800
>>> R13: ffff88107b82ab00 R14: 0000000000000003 R15: 0000000000000007
>>> FS:  00007fef64612700(0000) GS:ffff88087fc00000(0000) knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 0000000000000003 CR3: 000000087c2c7000 CR4: 00000000000407f0
>>> Stack:
>>> ffff88105d815d58 ffffffffa05199f0 ffff88105d815d88 ffff88087c3c9800
>>> ffff88087c3c9400 ffff88107b82ab00 ffff88087c3c9660 ffff88087c3c95c8
>>> ffff88105d815d78 ffffffffa0421ce9 ffff88087c3c9400 ffff88107b82aac0
>>> Call Trace:
>>> [<ffffffffa05199f0>] svc_xprt_enqueue+0x50/0x220 [sunrpc]
>>> [<ffffffffa0421ce9>] rdma_cma_handler+0x69/0x180 [svcrdma]
>>> [<ffffffffa039d086>] cma_remove_one+0x1f6/0x220 [rdma_cm]
>>> [<ffffffffa01dca86>] ib_unregister_device+0x46/0x120 [ib_core]
>>> [<ffffffffa032ddc9>] mlx4_ib_remove+0x29/0x260 [mlx4_ib]
>>> [<ffffffffa02fb9d0>] mlx4_remove_device+0xa0/0xc0 [mlx4_core]
>>> [<ffffffffa02fba2b>] mlx4_unregister_interface+0x3b/0xa0 [mlx4_core]
>>> [<ffffffffa033f4cc>] mlx4_ib_cleanup+0x10/0x23 [mlx4_ib]
>>> [<ffffffff810bd6b2>] SyS_delete_module+0x152/0x220
>>> [<ffffffff811496e4>] ? vm_munmap+0x54/0x70
>>> [<ffffffff815adca6>] system_call_fastpath+0x1a/0x1f
>>> Code: 5d c3 0f b7 17 66 39 ca 74 f6 f3 90 0f b7 17 66 39 d1 75 f6 5d c3
>>> 55 65 81 04 25 20 b9 00 00 00 02 00 00 48 89 e5 b8 00 00 01 00 <f0> 0f
>>> c1 07 89 c2 c1 ea 10 66 39 c2 75 04 5d c3 f3 90 0f b7 07
>>> RIP  [<ffffffff815a5c35>] _raw_spin_lock_bh+0x15/0x40
>>> RSP <ffff88105d815d18>
>>> CR2: 0000000000000003
>>> ---[ end trace 18e02ff413ac4b9b ]---
>>> Kernel panic - not syncing: Fatal exception in interrupt
>>> Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range:
>>> 0xffffffff80000000-0xffffffff9fffffff)
>>> ---[ end Kernel panic - not syncing: Fatal exception in interrupt
>>> 
>>> Kind regards,
>>> Klemens
>>> 
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>> 
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> 
> 
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com