From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shaohua Li <shaohua.li@intel.com>
Subject: [BUG report] lockdep deadlock warning in shutdown
Date: Fri, 03 Jun 2011 11:24:32 +0800
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To: "robert.moore" <robert.moore@intel.com>, "Lin, Ming M" <ming.m.lin@intel.com>
Cc: linux acpi <linux-acpi@vger.kernel.org>

running 3.0-rc1, shutting down my system triggers a lockdep deadlock
warning.

The deadlock warning is triggered when executing
acpi_hw_clear_acpi_status, stack trace is something like:
...
__lock_acquire
?acpi_os_acquire_lock
lock_acquire
?acpi_os_acquire_lock
?_raw_spin_lock_irqsave
?acpi_hw_enable_runtime_gpe_block
_raw_spin_lock_irqsave
?acpi_os_acquire_lock
?acpi-hw_write
acpi_os_acquire_lock
acpi_ev_walk_gpe_list
acpi_hw_clear_acpi_status
acpi_enter_sleep_state
...
I wrote it down by hand since this is shutdown, no way to get the log.
also since the screen scrolls fast, I didn't catch another code path the
locks are taken which lockdep prints out.

Thanks,
Shaohua