Issue

• Kernel crashes with following messages when trying to capture debug data from the mount /sys/kernel/debug:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
IP: [<ffffffffa0274444>] configfs_readdir+0xf4/0x230 [configfs]
PGD 35595e067 PUD b7bf60067 PMD 0 
Oops: 0000 [#1] SMP 
last sysfs file: /sys/module/ipv6/initstate
CPU 9 
Modules linked in: nfs fscache nfsd lockd nfs_acl auth_rpcgss exportfs dlm configfs mptctl mptbase sunrpc pcc_cpufreq bonding 8021q garp stp llc ipv6 dm_round_robin dm_multipath video output hpilo hpwdt microcode serio_raw iTCO_wdt iTCO_vendor_support power_meter sg be2net ioatdma dca shpchp ext4 mbcache jbd2 sd_mod crc_t10dif lpfc scsi_transport_fc scsi_tgt hpsa dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan]

Pid: 59185, comm: bpbkar Tainted: G        W  ---------------    2.6.32-279.1.1.el6.x86_64 #1
RIP: 0010:[<ffffffffa0274444>]  [<ffffffffa0274444>] configfs_readdir+0xf4/0x230 [configfs]
RSP: 0018:ffff8825a19d9e78  EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff883ff08d6ae0 RCX: ffff883ff08d6ad8
RDX: 0000000000000006 RSI: ffff883ff08d6a40 RDI: ffffffffa0349950
RBP: ffff8825a19d9ed8 R08: ffff883ff08d6ae0 R09: 0000000000000004
R10: 00000000000000a8 R11: 0000000000000246 R12: ffff883ff1b34800
R13: ffffffffa0349950 R14: ffff883ff08d6710 R15: ffff883ff08d6718
FS:  00007f6f6b40e720(0000) GS:ffff8820b0c20000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000040 CR3: 000000049744f000 CR4: 00000000000406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process bpbkar (pid: 59185, threadinfo ffff8825a19d8000, task ffff883d2f49caa0)
Stack:
 ffff8825a19d9ee8 0000000000000286 ffff883ff08d6ad8 ffffffff8118ef80
<d> ffff8825a19d9f38 ffff883ff08d6a40 ffff883ff37f9720 ffff883ff1b34800
<d> ffff8825a19d9f38 ffffffff8118ef80 ffff883ff37f9720 ffff883ff37f9668
Call Trace:
 [<ffffffff8118ef80>] ? filldir+0x0/0xe0
 [<ffffffff8118ef80>] ? filldir+0x0/0xe0
 [<ffffffff8118f200>] vfs_readdir+0xc0/0xe0
 [<ffffffff8117b0f2>] ? vfs_write+0x132/0x1a0
 [<ffffffff8118f389>] sys_getdents+0x89/0xf0
 [<ffffffff8100b0f2>] system_call_fastpath+0x16/0x1b
Code: 48 83 f8 02 4d 8d 7e 08 48 89 55 c8 0f 84 15 01 00 00 49 8b 5e 08 48 3b 5d c8 0f 85 7c 00 00 00 e9 da 00 00 00 66 90 48 8b 40 10 <4c> 8b 40 40 44 0f b7 49 44 4c 89 ee 49 8b 4c 24 40 48 8b 7d c0 
RIP  [<ffffffffa0274444>] configfs_readdir+0xf4/0x230 [configfs]
 RSP <ffff8825a19d9e78>
CR2: 0000000000000040

• Kernel crashes with following messages when trying to capture debug data for GFS2 issue from the mount /sys/kernel/debug:

------------[ cut here ]------------
kernel BUG at fs/configfs/dir.c:59!
invalid opcode: 0000 [#1] SMP 
last sysfs file: /sys/devices/pci0000:00/0000:00:03.0/0000:04:00.0/host3/rport-3:0-0/target3:0:0/3:0:0:0/state
CPU 19 
Modules linked in: bridge gfs2 dlm configfs autofs4 ipmi_devintf nfs lockd fscache auth_rpcgss nfs_acl lin_tape(U) sunrpc pcc_cpufreq bonding 8021q garp stp llc ipv6 xfs exportfs microcode serio_raw hpwdt hpilo iTCO_wdt iTCO_vendor_support ioatdma dca osst st ch power_meter sg tg3 be2net shpchp ext4 mbcache jbd2 raid1 dm_round_robin sd_mod crc_t10dif sr_mod cdrom iomemory_vsl(P)(U) qla2xxx scsi_transport_fc scsi_tgt hpsa pata_acpi ata_generic ata_piix dm_multipath dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan]

Pid: 63470, comm: glocktop Tainted: P           ---------------    2.6.32-358.14.1.el6.x86_64 #1 HP ProLiant DL380p Gen8
RIP: 0010:[<ffffffffa04b640b>]  [<ffffffffa04b640b>] configfs_d_iput+0x7b/0xa0 [configfs]
RSP: 0018:ffff882b6f63be48  EFLAGS: 00010287
RAX: ffffffffa04b6390 RBX: ffff881813d65710 RCX: 0000000000000001
RDX: ffff8804aec765d8 RSI: ffff8804aec765a8 RDI: ffff8817aac6d240
RBP: ffff882b6f63be58 R08: ffff8817aac6d290 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8804aec765a8
R13: ffff8804aec765a8 R14: ffff8817aac6d240 R15: ffff882fcb2fed80
FS:  00007fa721c10700(0000) GS:ffff88007db60000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa721c1f000 CR3: 0000000309fa1000 CR4: 00000000000407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process glocktop (pid: 63470, threadinfo ffff882b6f63a000, task ffff8820ef644040)
Stack:
 ffff8817aac6d240 ffff8804aec765a8 ffff882b6f63be78 ffffffff8119932c
<d> ffff8817aac6d240 ffff8817aac6d248 ffff882b6f63be98 ffffffff811994a1
<d> ffff8817aac6d240 ffff8817aac6d248 ffff882b6f63beb8 ffffffff8119b04c
Call Trace:
 [<ffffffff8119932c>] dentry_iput+0x7c/0x100
 [<ffffffff811994a1>] d_kill+0x31/0x60
 [<ffffffff8119b04c>] dput+0x7c/0x150
 [<ffffffff81182959>] __fput+0x189/0x210
 [<ffffffff81182a05>] fput+0x25/0x30
 [<ffffffff8117de5d>] filp_close+0x5d/0x90
 [<ffffffff8117df35>] sys_close+0xa5/0x100
 [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
Code: f6 43 40 01 75 e3 48 8b 7b 50 e8 01 2e cb e0 48 8b 3d 72 34 00 00 48 89 de e8 c2 26 cb e0 4c 89 e7 e8 8a 62 ce e0 5b 41 5c c9 c3 <0f> 0b eb fe be 9c 00 00 00 48 c7 c7 90 8a 4b a0 e8 20 7f bb e0 
RIP  [<ffffffffa04b640b>] configfs_d_iput+0x7b/0xa0 [configfs]
 RSP <ffff882b6f63be48>