BUG 802021 - hang in _pagebuf_find_lockable_buffer

[pv@xxxxxxxxxxxxx (nathans@xxxxxxxxxxxx)]

View Incident: 
http://co-op.engr.sgi.com/BugWorks/code/bwxquery.cgi?search=Search&wlong=1&view_type=Bug&wi=802021

Submitter : nathans                   Submitter Domain : engr               
Assigned Engineer : nb                Assigned Domain : sgi.com             
Assigned Group : xfs-linux            Category : software                   
Customer Reported : F                 Priority : 1                          
Project : xfs-linux                   Status : open                         
Description :
An XFS qa run hung my desktop machine over the weekend.  This
was using the top-of-tree source as of Sunday morning (localtime)
- I don't think anything has been checked in since - in qa test
number 013 (fsstress).

The machine was responsive to ping, but not to telnet/rlogin,
the kernel backtrace was as follows...


Entering kdb (current=0xc4622000, pid 5038) due to Keyboard Entry
kdb> bt
    EBP       EIP         Function(args)
0xc4623a1c 0xc0175976 _pagebuf_find_lockable_buffer+0x1c2 (0xc5aa80e0, 
0xc5aa6200, 0x8000, 0x0, 0x2000)
                               kernel .text 0xc0100000 0xc01757b4 0xc0175990
0xc4623a50 0xc01759ba _pagebuf_get_lockable_buffer+0x2a (0xc5aa80e0, 
0xc5aa6200, 0x8000, 0x0, 0x2000)
                               kernel .text 0xc0100000 0xc0175990 0xc0175a48
0xc4623a94 0xc017143f pagebuf_get+0x10b (0xc5aa80e0, 0x8000, 0x0, 0x2000, 
0x2201)
                               kernel .text 0xc0100000 0xc0171334 0xc017154c
0xc4623ac4 0xc01d45b0 xfs_trans_read_buf+0x48 (0xc5fa8800, 0x0, 0xc5fa8964, 
0x40, 0x0)
                               kernel .text 0xc0100000 0xc01d4568 0xc01d4af0
0xc4623b24 0xc01b6fff xfs_itobp+0x133 (0xc5fa8800, 0x0, 0xc43b6930, 0xc4623bec, 
0xc4623bf0)
                               kernel .text 0xc0100000 0xc01b6ecc 0xc01b7154
0xc4623c10 0xc01be777 xfs_bulkstat+0x87f (0xc5fa8800, 0x0, 0xc4623c9c, 
0xc4623c94, 0xc01bd9b0)
                               kernel .text 0xc0100000 0xc01bdef8 0xc01bea74
0xc4623f6c 0xc01e54f0 xfs_ioctl+0x540 (0xc1a590b8, 0xc34fa360, 0xc4e798a0, 
0xc0105865, 0xbffffb14)
                               kernel .text 0xc0100000 0xc01e4fb0 0xc01e5ea0
0xc4623f90 0xc01e4422 linvfs_ioctl+0x56 (0xc34fa360, 0xc4e798a0, 0xc0105865, 
0xbffffb14, 0xc4622000)
                               kernel .text 0xc0100000 0xc01e43cc 0xc01e442c
0xc4623fbc 0xc0136cf4 sys_ioctl+0x174 (0x3, 0xc0105865, 0xbffffb14, 0xbffffb34, 
0xbffffc74)
                               kernel .text 0xc0100000 0xc0136b80 0xc0136d10
           0xc0108e28 system_call+0x34
                               kernel .text 0xc0100000 0xc0108df4 0xc0108e2c
kdb> 
kdb> rd
eax = 0x00000000 ebx = 0xc46239bc ecx = 0x00002000 edx = 0x0000a000 
esi = 0xc3ff4e40 edi = 0xc46239c0 esp = 0xc4623994 eip = 0xc0175976 
ebp = 0xc4623a1c  ss = 0x00000018  cs = 0x00000010 eflags = 0x00000207 
 ds = 0xc4620018  es = 0xc0170018 origeax = 0xffffff01 &regs = 0xc4623960
kdb> id 0xc0175976
0xc0175976 _pagebuf_find_lockable_buffer+0x1c2:   movl   0x20(%ebp),%ecx
0xc0175979 _pagebuf_find_lockable_buffer+0x1c5:   movl   $0x0,(%ecx)
0xc017597f _pagebuf_find_lockable_buffer+0x1cb:   nop    
0xc0175980 _pagebuf_find_lockable_buffer+0x1cc:   xorl   %eax,%eax
0xc0175982 _pagebuf_find_lockable_buffer+0x1ce:   leal   0xffffff78(%ebp),%esp
0xc0175988 _pagebuf_find_lockable_buffer+0x1d4:   popl   %ebx
0xc0175989 _pagebuf_find_lockable_buffer+0x1d5:   popl   %esi
0xc017598a _pagebuf_find_lockable_buffer+0x1d6:   popl   %edi
0xc017598b _pagebuf_find_lockable_buffer+0x1d7:   movl   %ebp,%esp
0xc017598d _pagebuf_find_lockable_buffer+0x1d9:   popl   %ebp
0xc017598e _pagebuf_find_lockable_buffer+0x1da:   ret    
0xc017598f _pagebuf_find_lockable_buffer+0x1db:   nop    
0xc0175990 _pagebuf_get_lockable_buffer:   pushl  %ebp
0xc0175991 _pagebuf_get_lockable_buffer+0x1:   movl   %esp,%ebp
0xc0175993 _pagebuf_get_lockable_buffer+0x3:   subl   $0x4,%esp
0xc0175996 _pagebuf_get_lockable_buffer+0x6:   pushl  %edi
kdb>