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authorPeter Zijlstra <peterz@infradead.org>2015-02-26 16:23:11 +0100
committerIngo Molnar <mingo@kernel.org>2015-03-23 10:49:07 +0100
commit35a9393c95b31870a74f51a3e7455f33f5657b6f (patch)
tree9a0e913b3d2dc02956c03a24b535a3604bb2dfa7 /README
parentbc465aa9d045feb0e13b4a8f32cc33c1943f62d6 (diff)
downloadlinux-35a9393c95b31870a74f51a3e7455f33f5657b6f.tar.bz2
lockdep: Fix the module unload key range freeing logic
Module unload calls lockdep_free_key_range(), which removes entries from the data structures. Most of the lockdep code OTOH assumes the data structures are append only; in specific see the comments in add_lock_to_list() and look_up_lock_class(). Clearly this has only worked by accident; make it work proper. The actual scenario to make it go boom would involve the memory freed by the module unlock being re-allocated and re-used for a lock inside of a rcu-sched grace period. This is a very unlikely scenario, still better plug the hole. Use RCU list iteration in all places and ammend the comments. Change lockdep_free_key_range() to issue a sync_sched() between removal from the lists and returning -- which results in the memory being freed. Further ensure the callers are placed correctly and comment the requirements. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Tsyvarev <tsyvarev@ispras.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
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