This is something I'm getting with latest Linus git. The machine is connected over serial cable and the below lockdep splat appears on the serial console. I won't be able to test patches or other stuff in the next couple of days but I've seen this on a bunch of machines so far so it should be pretty easy to reproduce on any generic setup: simply do 'halt' on the command line and stare the the serial console output coming out on another machine. I'm attaching dmesg and .config. Thanks. INIT: Switching to runINIT: Sending procUsing makefile-style concurrent boot in runlevel 0. Stopping deferred execution scheduler: atd. fuse exit Shutting down ALSA...done. Asking all remaining processes to terminate...done. All processes ended within 1 seconds....done. Stopping enhanced syslogd: rsyslogd. Saving the system clock. Cannot access the Hardware Clock via any known method. Use the --debug option to see the details of our search for an access method. Deconfiguring network interfaces...done. Cleaning up ifupdown.... Deactivating swap...done. Unmounting local filesystems...done. Will now halt. Shutdown: hdd Shutdown: hda ACPI Exception: AE_AML_PACKAGE_LIMIT, Index (0x0000000000000007) is beyond end of object (20110413/exoparg2-418) ACPI Error: Method parse/execution failed [\_SB_.PCI0.IDE0.GTM_] (Node de04f2c0), AE_AML_PACKAGE_LIMIT (20110413/pspars) ACPI Error: Method parse/execution failed [\_SB_.PCI0.IDE0.CHN0._GTM] (Node de04f470), AE_AML_PACKAGE_LIMIT (20110413/p) ehci_hcd 0000:00:1d.7: PCI INT D disabled ACPI: Preparing to enter system sleep state S5 Disabling non-boot CPUs ... lockdep: fixing up alternatives. Power down. acpi_power_off called ============================================= [ INFO: possible recursive locking detected ] 3.0.0-rc3-00256-gde505e7 #7 --------------------------------------------- halt/2507 is trying to acquire lock: (&(lock)->rlock){......}, at: [<c1177baf>] acpi_os_acquire_lock+0xd/0xf but task is already holding lock: (&(lock)->rlock){......}, at: [<c1177baf>] acpi_os_acquire_lock+0xd/0xf other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(lock)->rlock); lock(&(lock)->rlock); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by halt/2507: #0: (reboot_mutex){+.+.+.}, at: [<c1041e04>] sys_reboot+0x80/0x140 #1: (&(lock)->rlock){......}, at: [<c1177baf>] acpi_os_acquire_lock+0xd/0xf stack backtrace: Pid: 2507, comm: halt Not tainted 3.0.0-rc3-00256-gde505e7 #7 Call Trace: [<c105b758>] __lock_acquire+0x139b/0x141b [<c1361385>] ? _raw_spin_unlock_irqrestore+0x34/0x5e [<c1177baf>] ? acpi_os_acquire_lock+0xd/0xf [<c105bc33>] lock_acquire+0xb0/0xcf [<c1177baf>] ? acpi_os_acquire_lock+0xd/0xf [<c1360d82>] _raw_spin_lock_irqsave+0x33/0x43 [<c1177baf>] ? acpi_os_acquire_lock+0xd/0xf [<c1177baf>] acpi_os_acquire_lock+0xd/0xf [<c118620f>] acpi_ev_walk_gpe_list+0x1e/0x6e [<c118c271>] ? acpi_hw_enable_runtime_gpe_block+0x38/0x38 [<c118c752>] acpi_hw_clear_acpi_status+0x37/0x4b [<c118cc81>] acpi_enter_sleep_state+0x87/0x1ae [<c1058213>] ? trace_hardirqs_off+0xb/0xd [<c1179380>] ? acpi_power_off+0x1d/0x29 [<c1179387>] acpi_power_off+0x24/0x29 [<c10151ab>] native_machine_power_off+0x26/0x28 [<c10151bb>] machine_power_off+0xe/0x10 [<c1041c17>] kernel_power_off+0x40/0x43 [<c1041e6d>] sys_reboot+0xe9/0x140 [<c103fc74>] ? do_send_sig_info+0x54/0x5f [<c103ffce>] ? kill_pid_info+0x76/0x80 [<c1040219>] ? sys_kill+0xb2/0x180 [<c10d6e7e>] ? vfsmount_lock_local_unlock+0x3a/0x50 [<c10d6f13>] ? mntput_no_expire+0x26/0xd8 [<c10d6fe3>] ? mntput+0x1e/0x20 [<c10c2365>] ? fput+0x17a/0x183 [<c1156b90>] ? trace_hardirqs_on_thunk+0xc/0x10 [<c13660c3>] ? sysenter_exit+0xf/0x18 [<c10592ba>] ? trace_hardirqs_on_caller+0x10a/0x12b [<c1366090>] sysenter_do_call+0x12/0x36 -- Regards/Gruss, Boris. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html