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Subject[PATCH] lockdep: fix mismatched lockdep_depth/curr_chain_hash
Hi Greg,
Here is the backported version of the patch. I applied it on top of Let me know if you have any issues.


lockdep: fix mismatched lockdep_depth/curr_chain_hash

It is possible for the current->curr_chain_key to become inconsistent with the
current index if the chain fails to validate. The end result is that future
lock_acquire() operations may inadvertently fail to find a hit in the cache
resulting in a new node being added to the graph for every acquire.

[ peterz: this might explain some of the lockdep is so _slow_ complaints. ]
[ mingo: this does not impact the correctness of validation, but may slow
down future operations significantly, if the chain gets very long. ]

Signed-off-by: Gregory Haskins <>
Signed-off-by: Peter Zijlstra <>
Signed-off-by: Ingo Molnar <>

kernel/lockdep.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 1a5ff22..072cf25 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2166,7 +2166,6 @@ out_calc_hash:
chain_key = iterate_chain_key(chain_key, id);
- curr->curr_chain_key = chain_key;

* Trylock needs to maintain the stack of held locks, but it
@@ -2215,6 +2214,7 @@ out_calc_hash:
if (unlikely(!debug_locks))
return 0;

+ curr->curr_chain_key = chain_key;
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