While running hackbench against today's next-20100208 (9056d31..)
on a s390 box, came across following BUG.

kjournald starting.  Commit interval 5 seconds
EXT3-fs (dasdb1): using internal journal
EXT3-fs (dasdb1): mounted filesystem with writeback data mode
BUG: Dentry 00000000fc937d40{i=13c39,n=bin} still in use (1) İunmount of ext3 da
sdb1¨
------------" cut here "------------
kernel BUG at fs/dcache.c:676!
illegal operation: 0001 "#1" SMP
Modules linked in: fuse loop zfcp scsi_transport_fc qeth_l3 scsi_tgt ipv6 vmur s
csi_mod ext3 jbd mbcache dasd_eckd_mod dasd_fba_mod dasd_mod qeth qdio ccwgroup
dm_mod
CPU: 2 Not tainted 2.6.33-rc7-autotest-next-20100208-5-default #1
Process umount (pid: 2120, task: 00000000fb3da538, ksp: 00000000fc6c7b80)
Krnl PSW : 0704100180000000 000000000023ef54 (shrink_dcache_for_umount_subtree+0
x3a8/0x3d0)
           R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0 EA:3
Krnl GPRS: 0000000000010000 0000000000686648 000000000000005c 00000000fffffffd
           0000000000448a52 0000000000000000 0000000000000001 0000000000000001
           00000000000000e0 000000000060ba00 00000000fc937ce0 0000000000623218
           00000000fae10e68 000000000046ced8 000000000023ef50 00000000fc6c7cf8
Krnl Code: 000000000023ef44: e3c0f0a80024       stg     %r12,168(%r15)
           000000000023ef4a: c0e500104d5b       brasl   %r14,448a00
           000000000023ef50: a7f40001           brc     15,23ef52
          >000000000023ef54: a7f40000           brc     15,23ef54
           000000000023ef58: c0b0001f2160       larl    %r11,623218
           000000000023ef5e: a7f4fe79           brc     15,23ec50
           000000000023ef62: c020001e654f       larl    %r2,60ba00
           000000000023ef68: c0e50007229c       brasl   %r14,3234a0
Call Trace:
(<000000000023ef50> shrink_dcache_for_umount_subtree+0x3a4/0x3d0)
 <000000000023efde> shrink_dcache_for_umount+0x62/0x98
 <000000000022a234> generic_shutdown_super+0x3c/0x160
 <000000000022a38e> kill_block_super+0x36/0x54
 <000000000022ad38> deactivate_super+0xa0/0xc8
 <000000000024785e> SyS_umount+0x72/0x404
 <0000000000118c26> sysc_noemu+0x10/0x16
 <0000020000149836> 0x20000149836
Last Breaking-Event-Address:
 "<000000000023ef50>" shrink_dcache_for_umount_subtree+0x3a4/0x3d0

Did not observe this with next-20100205. Also there doesn't seem to be
any patches applied to this code after the last release. So not
sure what could have caused this. Corresponding code is :

 664                         if (atomic_read(&dentry->d_count) != 0) {
 665                                 printk(KERN_ERR
 666                                        "BUG: Dentry %p{i=%lx,n=%s}"
 667                                        " still in use (%d)"
 668                                        " [unmount of %s %s]\n",
 669                                        dentry,
 670                                        dentry->d_inode ?
 671                                        dentry->d_inode->i_ino : 0UL,
 672                                        dentry->d_name.name,
 673                                        atomic_read(&dentry->d_count),
 674                                        dentry->d_sb->s_type->name,
 675                                        dentry->d_sb->s_id);
 676                                 BUG();
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 677                         }

Let me know if i can provide any other information. Have attached
the config.

Thanks
-Sachin


-- 

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Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
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