Re: net/sunrpc Bug ? Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 on kernel 5.2.37

[Trond Myklebust]

On Sun, 2020-04-19 at 14:22 +0800, Sun Ted wrote:
> Hi Forks,
> 
> On the kernel version 5.2.37 or a bit earlier, running pressure
> testing with module insert & remove, actually the inserted module is
> not special and could be anyone.
> After dozens of testing, there will be throw below call trace and the
> system hung.
> 
> Testing script for insert & remove module like below:
>              for each in {1..100} ; do echo "$each" ; insmod
> openvswitch.ko ;  rmmod  openvswitch.ko ; usleep 100000 ; done
> The target machine is: arm64, cortex a53.
> 
> Disassembled the line " __wake_up_common_lock+0x98/0xe0 ", it located
> the code "include/linux/spinlock.h" , it should be using the NULL
> pointer "lock->rlock "
> 
> static __always_inline void spin_unlock_irqrestore(spinlock_t *lock,
> unsigned long flags)
> {
>         raw_spin_unlock_irqrestore(&lock->rlock, flags);
> 
> Did you ever see this issue or have a fix for this based on kernel
> 5.2.37 version?
> 
> Call trace:
> openvswitch: Open vSwitch switching datapath
> Unable to handle kernel NULL pointer dereference at virtual address
> 0000000000000000
> Mem abort info:
>   ESR = 0x86000005
>   Exception class = IABT (current EL), IL = 32 bits
>   SET = 0, FnV = 0
>   EA = 0, S1PTW = 0
> user pgtable: 4k pages, 39-bit VAs, pgdp=00000008f2ea9000
> [0000000000000000] pgd=0000000000000000, pud=0000000000000000
> Internal error: Oops: 86000005 [#1] PREEMPT SMP
> Modules linked in: openvswitch hse sch_fq_codel nsh nf_conncount
> nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 [last unloaded:
> openvswitch]
> CPU: 2 PID: 209 Comm: kworker/u9:3 Not tainted 5.2.37-yocto-standard
> #1
> Hardware name: Freescale S32G275 (DT)
> Workqueue: xprtiod xs_stream_data_receive_workfn
> pstate: 80000085 (Nzcv daIf -PAN -UAO)
> pc : 0x0
> lr : __wake_up_common+0x90/0x150
> sp : ffffff801146ba60
> x29: ffffff801146ba60 x28: ffffff8010d36000
> x27: ffffff801146bb90 x26: 0000000000000000
> x25: 0000000000000003 x24: 0000000000000000
> x23: 0000000000000001 x22: ffffff801146bb00
> x21: ffffff8010d351e8 x20: 0000000000000000
> x19: ffffff80112c37a0 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000
> x15: 0000000000000000 x14: 0000000000000000
> x13: 0000003002000000 x12: 0000902802000000
> x11: 0000000000000000 x10: 000001000000ed01
> x9 : 0000010000000000 x8 : 9b5e0000000048a6
> x7 : 0000000000000068 x6 : ffffff80112c37a0
> x5 : 0000000000000000 x4 : ffffff801146bb90
> x3 : ffffff801146bb90 x2 : 0000000000000000
> x1 : 0000000000000003 x0 : ffffff80112c37a0
> Call trace:
>  0x0
>  __wake_up_common_lock+0x98/0xe0
>  __wake_up+0x40/0x50
>  wake_up_bit+0x8c/0xb8
>  rpc_make_runnable+0xc8/0xd0
>  rpc_wake_up_task_on_wq_queue_action_locked+0x110/0x278
>  rpc_wake_up_queued_task.part.0+0x40/0x58
>  rpc_wake_up_queued_task+0x38/0x48
>  xprt_complete_rqst+0x68/0x128
>  xs_read_stream.constprop.0+0x2ec/0x3d0
>  xs_stream_data_receive_workfn+0x60/0x190
>  process_one_work+0x1bc/0x440
>  worker_thread+0x50/0x408
>  kthread+0x104/0x130
>  ret_from_fork+0x10/0x1c
> Code: bad PC value
> Kernel panic - not syncing: Fatal exception in interrupt
> SMP: stopping secondary CPUs
> Kernel Offset: disabled
> CPU features: 0x0002,2000200c
> Memory Limit: none
> 

I don't see why NFS would care about the openswitch module being loaded
or not, and so given your stack dump, I suspect this is more about a
corruption of the global bit_wait_table.

Cc: netdev@xxxxxxxxxxxxxxx to see if anyone there is aware of any
recent module cleanup issues with openswitch.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx