When a kernel module is repeatedly load and unload, it will eventually exhaust the lockdep entries resulting in a bug message. This is a use case that the current lockdep code cannot support.
This patchset tracks the number of zapped classes and print a warning if too many lockdep entries are wasted because of too many module unloading. For example, [ 2490.651531] BUG: MAX_LOCKDEP_KEYS too low! [ 2490.669925] turning off the locking correctness validator. [ 2490.669925] Please attach the output of /proc/lock_stat to the bug report [ 2490.669926] ======================================================== [ 2490.669927] WARNING: 6499 out of 8191 locks have been destroyed [ 2490.669927] through kernel module unload operations. [ 2490.669928] The corresponding lockdep entries are not reusable. [ 2490.669928] The system might have run out of lockdep entries because [ 2490.669929] of repeated kernel module load and unload operations. [ 2490.669929] Lockdep cannot support this particular use case. [ 2490.669930] -------------------------------------------------------- Waiman Long (2): locking/lockdep: Annotate #else/#endif's that are far from #if locking/lockdep: Track number of zapped classes & report abuse kernel/locking/lockdep.c | 42 ++++++++++++++++++++++++++++++-------- kernel/locking/lockdep_internals.h | 1 + kernel/locking/lockdep_proc.c | 2 ++ 3 files changed, 37 insertions(+), 8 deletions(-) -- 1.8.3.1
