Messages in this thread | | | Subject | Re: [PATCH] sched: Avoid that __wait_on_bit_lock() hangs | From | Bart Van Assche <> | Date | Wed, 3 Aug 2016 11:56:16 -0700 |
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On 08/03/2016 11:11 AM, Peter Zijlstra wrote: > That seems to do the right thing, so clearly I misunderstand. Please > clarify.
Hello Peter,
try_to_wake_up() locks task_struct.pi_lock but abort_exclusive_wait() not. My assumption is that the following sequence of events leads to the lockup that I had mentioned in the description of my patch: * try_to_wake_up() is called for the task that will execute abort_exclusive_wait(). * After try_to_wake_up() has checked task_struct.state and before autoremove_wake_function() has tried to remove the task from the wait queue, abort_exclusive_wait() is executed for the same task.
Please note that the call stack I had mentioned in my e-mail had been reported before. See e.g. * Michael Shaver, Kernel deadlock during mdadm reshape, July 2016 (http://www.spinics.net/lists/raid/msg53056.html). * Bart Van Assche, Kernel hangs in truncate_inode_pages(), August 2012 (https://lkml.org/lkml/2012/8/24/185).
Bart.
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