In a Ubuntu-Precise server (3.2.0-27 kernel) i have this kernel panic in dmesg:


[  131.459333] ------------[ cut here ]------------
[  131.459344] WARNING: at /build/buildd/linux-3.2.0/mm/slub.c:3374 ksize+0xb5/0xc0()
[  131.459347] Hardware name: ProLiant ML350 G6
[  131.459349] Modules linked in: ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack ipt_REJECT xt_CHECKSUM iptable_mangle xt_tcpudp iptable_filter ip_tables x_tables bridge stp xen_gntdev xen_netback xen_blkback xen_evtchn xenfs microcode usbhid hid usb_storage uas xfs radeon ttm drm_kms_helper drm ipmi_si ipmi_msghandler i2c_algo_bit psmouse i7core_edac bonding edac_core hpilo serio_raw shpchp acpi_power_meter mac_hid lp parport tg3 hpsa
[  131.459394] Pid: 1649, comm: sh Not tainted 3.2.0-27-generic #43-Ubuntu
[  131.459396] Call Trace:
[  131.459404]  [<ffffffff8106729f>] warn_slowpath_common+0x7f/0xc0
[  131.459410]  [<ffffffff81659eae>] ? _raw_spin_unlock_irqrestore+0x1e/0x30
[  131.459414]  [<ffffffff810672fa>] warn_slowpath_null+0x1a/0x20
[  131.459418]  [<ffffffff81161f65>] ksize+0xb5/0xc0
[  131.459423]  [<ffffffff811329bc>] kzfree+0x1c/0x40
[  131.459428]  [<ffffffff812d6b9a>] apparmor_file_free_security+0x1a/0x20
[  131.459434]  [<ffffffff8129dbc6>] security_file_free+0x16/0x20
[  131.459439]  [<ffffffff81179436>] __fput+0xc6/0x210
[  131.459442]  [<ffffffff811795a5>] fput+0x25/0x30
[  131.459446]  [<ffffffff811761c6>] filp_close+0x66/0x90
[  131.459450]  [<ffffffff81069b7a>] put_files_struct.part.10+0x7a/0xe0
[  131.459455]  [<ffffffff8106b598>] put_files_struct+0x18/0x20
[  131.459459]  [<ffffffff8106b664>] exit_files+0x54/0x70
[  131.459463]  [<ffffffff8106bb45>] do_exit+0x195/0x420
[  131.459467]  [<ffffffff8106bf74>] do_group_exit+0x44/0xa0
[  131.459470]  [<ffffffff8106bfe7>] sys_exit_group+0x17/0x20
[  131.459475]  [<ffffffff81662282>] system_call_fastpath+0x16/0x1b
[  131.459478] ---[ end trace 92e87a495e3a2e5a ]---
[  131.459487] ------------[ cut here ]------------
[  131.459564] kernel BUG at /build/buildd/linux-3.2.0/mm/slub.c:3430!
[  131.459660] invalid opcode: 0000 [#1] SMP 
[  131.459738] CPU 5 
[  131.459771] Modules linked in: ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack ipt_REJECT xt_CHECKSUM iptable_mangle xt_tcpudp iptable_filter ip_tables x_tables bridge stp xen_gntdev xen_netback xen_blkback xen_evtchn xenfs microcode usbhid hid usb_storage uas xfs radeon ttm drm_kms_helper drm ipmi_si ipmi_msghandler i2c_algo_bit psmouse i7core_edac bonding edac_core hpilo serio_raw shpchp acpi_power_meter mac_hid lp parport tg3 hpsa
[  131.460775] 
[  131.460802] Pid: 1649, comm: sh Tainted: G        W    3.2.0-27-generic #43-Ubuntu HP ProLiant ML350 G6
[  131.460996] RIP: e030:[<ffffffff81162505>]  [<ffffffff81162505>] kfree+0x135/0x140
[  131.461121] RSP: e02b:ffff88003126dd48  EFLAGS: 00010246
[  131.461203] RAX: 0000000000000000 RBX: ffff880000000000 RCX: 0000000000000000
[  131.461311] RDX: ffffffff7fffffff RSI: 0000000000000000 RDI: ffff880000000000
[  131.465056] RBP: ffff88003126dd78 R08: ffffea0000000000 R09: ffff880000000000
[  131.468879] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000008
[  131.472689] R13: ffff88002b8a10c0 R14: ffffffff811329d1 R15: ffff88002b8793b0
[  131.476640] FS:  00007f925fdfc700(0000) GS:ffff88003eea0000(0000) knlGS:0000000000000000
[  131.480675] CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
[  131.484618] CR2: 000000000061cd64 CR3: 0000000001c05000 CR4: 0000000000002660
[  131.488548] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  131.492424] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  131.496321] Process sh (pid: 1649, threadinfo ffff88003126c000, task ffff8800036716f0)
[  131.500220] Stack:
[  131.504003]  ffff88003126dd58 ffff880000000000 0000000000000008 ffff88002b8a10c0
[  131.507940]  ffff88002b8793b0 ffff88002b8793b0 ffff88003126dd98 ffffffff811329d1
[  131.511852]  0000000000000008 ffff88002f4e4800 ffff88003126dda8 ffffffff812d6b9a
[  131.515843] Call Trace:
[  131.519679]  [<ffffffff811329d1>] kzfree+0x31/0x40
[  131.523506]  [<ffffffff812d6b9a>] apparmor_file_free_security+0x1a/0x20
[  131.527416]  [<ffffffff8129dbc6>] security_file_free+0x16/0x20
[  131.527420]  [<ffffffff81179436>] __fput+0xc6/0x210
[  131.527423]  [<ffffffff811795a5>] fput+0x25/0x30
[  131.527428]  [<ffffffff811761c6>] filp_close+0x66/0x90
[  131.527432]  [<ffffffff81069b7a>] put_files_struct.part.10+0x7a/0xe0
[  131.527436]  [<ffffffff8106b598>] put_files_struct+0x18/0x20
[  131.527439]  [<ffffffff8106b664>] exit_files+0x54/0x70
[  131.527443]  [<ffffffff8106bb45>] do_exit+0x195/0x420
[  131.527446]  [<ffffffff8106bf74>] do_group_exit+0x44/0xa0
[  131.527450]  [<ffffffff8106bfe7>] sys_exit_group+0x17/0x20
[  131.527454]  [<ffffffff81662282>] system_call_fastpath+0x16/0x1b
[  131.527456] Code: 89 da 4c 89 c6 e8 d6 34 4e 00 eb 94 49 f7 00 00 c0 00 00 74 16 4c 89 c7 e8 39 17 fc ff e9 7e ff ff ff 4d 8b 40 30 e9 27 ff ff ff <0f> 0b 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 53 48 83 ec 08 66 
[  131.527481] RIP  [<ffffffff81162505>] kfree+0x135/0x140
[  131.527486]  RSP <ffff88003126dd48>
[  131.527513] ---[ end trace 92e87a495e3a2e5b ]---
[  131.527515] Fixing recursive fault but reboot is needed!

Hardware is a HP Proliant G5 with Ubuntu Server.

setting a grub-kernel parameters "acpi=off noapic" fix this issue.