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Peter Zijlstra authored
Lockdep thinks there's lock recursion through: kmem_cache_free() cache_flusharray() spin_lock(&l3->list_lock) <----------------. free_block() | slab_destroy() | call_rcu() | debug_object_activate() | debug_object_init() | __debug_object_init() | kmem_cache_alloc() | cache_alloc_refill() | spin_lock(&l3->list_lock) --' Now debug objects doesn't use SLAB_DESTROY_BY_RCU and hence there is no actual possibility of recursing. Luckily debug objects marks it slab with SLAB_DEBUG_OBJECTS so we can identify the thing. Mark all SLAB_DEBUG_OBJECTS (all one!) slab caches with a special lockdep key so that lockdep sees its a different cachep. Also add a WARN on trying to create a SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS cache, to avoid possible future trouble. Reported-and-tested-by:
Sebastian Siewior <sebastian@breakpoint.cc> [ fixes to the initial patch ] Reported-by:
Thomas Gleixner <tglx@linutronix.de> Acked-by:
Pekka Enberg <penberg@kernel.org> Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1311341165.27400.58.camel@twinsSigned-off-by:
Ingo Molnar <mingo@elte.hu>
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