On Thu, Apr 28, 2016 at 1:44 PM, Josh Poimboeuf [off-list ref] wrote:

A preempted function might not have had a chance to save the frame
pointer to the stack yet, which can result in its caller getting skipped
on a stack trace.

Add a flag to indicate when the task has been preempted so that stack
dump code can determine whether the stack trace is reliable.

I think I like this, but how do you handle the rather similar case in
which a task goes to sleep because it's waiting on IO that happened in
response to get_user, put_user, copy_from_user, etc?

--Andy