Messages in this thread | | | Date | Thu, 13 Oct 2011 20:09:13 -0400 | From | Ben Blum <> | Subject | BUG: cgroup_task_counter subsys may crash with whole-threadgroup move |
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I was testing some patches for cgroup_attach_proc and managed to cause a crash with the following usage pattern:
mount -t cgroup none -o tasks /dev/cgroup cd /dev/cgroup mkdir foo echo $PID > foo/cgroup.procs echo $PID > tasks echo $PID > foo/cgroup.procs
Where $PID is the thread ID of a member of a multithreaded process (my test program just does CLONE_THREAD 8 times and then all threads sleep). (It doesn't matter if the thread is the group leader or not, but a single-threaded process doesn't crash.)
And get the following kernel panic: http://maximegalon.andrew.cmu.edu/cgroup-taskstats/panic.txt
It's deterministic, and happens only when the "tasks" subsystem is mounted.
I'm using user-mode linux to test, with the following config: http://maximegalon.andrew.cmu.edu/cgroup-taskstats/config.txt
and I ran it in GDB to get the following backtrace: http://maximegalon.andrew.cmu.edu/cgroup-taskstats/bt.txt
Thanks, Ben
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