NFS swap hangup

Hello.

Your commit 15001e5a7e1e207b6bd258cd8f187814cd15b6dc is hang up in my system.

Lock detector said
NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapon:933]

Modules linked in:                                                              
                                                                                
CPU: 0 PID: 933 Comm: swapon Not tainted 4.6.0-rc5-08195-g94cf084-dirty #884    
task: 8f026240 ti: 8f10a000 task.ti: 8f10a000                                   
PC is at xprt_iter_next_entry_multiple+0x22/0xd0                                
PR is at xprt_iter_next_entry_all+0xc/0x1c                                      

PC : 8c32920a SP : 8f10be4c SR : 40008000 TEA : c00a3000 R0 : 8c3291e8 R1 : 8f06f6e0 R2 : 8f06f6e0 R3 : 00000001 R4 : 8f10bebc R5 : 8c3290e8 R6 : 00000000 R7 : 00000020 R8 : 8c3292d4 R9 : 8f10bebc R10 : 8c313320 R11 : 8f10bebc R12 : 8f06b000 R13 : 8c313864 R14 : 8f10be4c
MACH: 00000007 MACL: 00001300 GBR : 29579bd0 PR : 8c3292e0

Call trace:                                                                     
 [<8c3290e8>] xprt_switch_find_next_entry+0x0/0x38                              
 [<8c039c38>] __lock_acquire.isra.16+0x0/0xaa0                                  
 [<8c3292e0>] xprt_iter_next_entry_all+0xc/0x1c                                 
 [<8c313864>] xprt_put+0x0/0x64                                                 
 [<8c310198>] rpc_clnt_swap_activate_callback+0x0/0x18                          
 [<8c313320>] xprt_get+0x0/0x88                                                 
 [<8c3292d4>] xprt_iter_next_entry_all+0x0/0x1c                                 
 [<8c329140>] xprt_iter_get_helper+0x20/0x38                                    
 [<8c329852>] xprt_iter_get_next+0x32/0x6c                                      
 [<8c329820>] xprt_iter_get_next+0x0/0x6c                                       
 [<8c329120>] xprt_iter_get_helper+0x0/0x38                                     
 [<8c329820>] xprt_iter_get_next+0x0/0x6c                                       
 [<8c310c5c>] rpc_clnt_iterate_for_each_xprt+0x80/0xd8                          
 [<8c310bdc>] rpc_clnt_iterate_for_each_xprt+0x0/0xd8                           
 [<8c312470>] rpc_clnt_swap_activate+0x4c/0x70                                  
 [<8c310bdc>] rpc_clnt_iterate_for_each_xprt+0x0/0xd8                           
 [<8c00376c>] arch_local_irq_restore+0x0/0x2c                                   
 [<8c170d30>] nfs_swap_activate+0x28/0x38                                       
 [<8c0aaf42>] SyS_swapon+0x96a/0xf24                                            
 [<8c0e94d4>] fsnotify+0x0/0x31c                                                
 [<8c0c6ae4>] dput+0x0/0x244                                                    
 [<8c0cec1c>] mntput+0x0/0x30                                                   
 [<8c048630>] call_rcu_sched+0x0/0x1c                                           
 [<8c0b3e68>] __fput+0xfc/0x1f0                                                 
 [<8c0b3fc2>] ____fput+0xa/0x18                                                 
 [<8c008242>] syscall_call+0x18/0x1e                                            
 [<8c0aa5d8>] SyS_swapon+0x0/0xf24                                              

2 locks held by swapon/933: x
#0: (&sb->s_type->i_mutex_key#6){......}, at: [<8c0aa7ae>] SyS_swapon+0x1d6/0
f24
#1: (rcu_read_lock){......}, at: [<8c329820>] xprt_iter_get_next+0x0/0x6c

Code:                                                                           
  8c329204:  mov.l     r5, @r14                                                 
  8c329206:  mov.l     @(44,r1), r3                                             
  8c329208:  mov       r1, r2                                                   
->8c32920a:  mov       #1, r0                                                   
  8c32920c:  add       #48, r2                                                  
  8c32920e:  cmp/hi    r0, r3                                                   
  8c329210:  bf.s      8c32926a                                                 
  8c329212:  mov.l     r2, @(4,r14)                                             
  8c329214:  mov.l     @(4,r4), r8                                              

Is anything invastigate?

Thanks.

Yoshinori Sato
<[email protected]>