linux-kernel - [PATCH 0/5] locking/lockdep: Reuse zapped chain

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Date:   Thu, 12 Dec 2019 17:35:20 -0500
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>
Cc:     linux-kernel@...r.kernel.org, Bart Van Assche <bvanassche@....org>,
        Waiman Long <longman@...hat.com>
Subject: [PATCH 0/5] locking/lockdep: Reuse zapped chain_hlocks entries

It was found that when running a workload that kept on adding lock
classes and then zapping them repetitively, the system will eventually
running out of chain_hlocks[] entries even though there were still
plenty of other lockdep data buffers available.

  [ 4318.443670] BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!
  [ 4318.444809] turning off the locking correctness validator.

In order to fix this problem, we have to make chain_hlocks[] entries
reusable just like other lockdep arrays. Besides that, the patchset
also adds some zapped class and chain_hlocks counters to be tracked by
/proc/lockdep_stats. It also fixes leakage in the irq context counters.

Waiman Long (5):
  locking/lockdep: Track number of zapped classes
  locking/lockdep: Track leaked chain_hlocks entries
  locking/lockdep: Track number of zapped lock chains
  locking/lockdep: Reuse free chain_hlocks entries
  locking/lockdep: Decrement irq context counters when removing lock
    chain

 kernel/locking/lockdep.c           | 201 ++++++++++++++++++++++-------
 kernel/locking/lockdep_internals.h |  23 +++-
 kernel/locking/lockdep_proc.c      |  17 ++-
 3 files changed, 189 insertions(+), 52 deletions(-)

-- 
2.18.1