Question about semaphores and threads

[Marc CHALAND]

Here is some more info about this log :
Each time this log appears, the state of the thread into jdb is, for example :

17.0d  (deleted)        a0      17.01     rcv,ipc_progr

Backtrace of each thread is mainly :
l4rm_detach
l4th_pages_free
__do_cleanup_and_block

We observed one thread with the following backtrace :
__modify_region
l4rm_detach
l4th_pages_free
__do_cleanup_and_block

If I understand, the thread is quite dead but it still tries to do
semaphore, isn't it ?

Regards
Marc