https://github.com/torvalds/linux
Revision cee34d88cabd1ba5fc93e09b5b12232bc9338c7c authored by Peter Zijlstra on 02 June 2015, 10:50:13 UTC, committed by Ingo Molnar on 07 June 2015, 13:46:30 UTC
The lock_class iteration of /proc/lock_stat is not serialized against the lockdep_free_key_range() call from module unload. Therefore it can happen that we find a class of which ->name/->key are no longer valid. There is a further bug in zap_class() that left ->name dangling. Cure this. Use RCU_INIT_POINTER() because NULL. Since lockdep_free_key_range() is rcu_sched serialized, we can read both ->name and ->key under rcu_read_lock_sched() (preempt-disable) and be assured that if we observe a !NULL value it stays safe to use for as long as we hold that lock. If we observe both NULL, skip the entry. Reported-by: Jerome Marchand <jmarchan@redhat.com> Tested-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20150602105013.GS3644@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent 37ef164
Tip revision: cee34d88cabd1ba5fc93e09b5b12232bc9338c7c authored by Peter Zijlstra on 02 June 2015, 10:50:13 UTC
lockdep: Fix a race between /proc/lock_stat and module unload
lockdep: Fix a race between /proc/lock_stat and module unload
Tip revision: cee34d8
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