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From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org,
	Bart Van Assche <bvanassche@acm.org>,
	Waiman Long <longman@redhat.com>
Subject: [PATCH 0/5] locking/lockdep: Reuse zapped chain_hlocks entries
Date: Thu, 12 Dec 2019 17:35:20 -0500	[thread overview]
Message-ID: <20191212223525.1652-1-longman@redhat.com> (raw)

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


             reply	other threads:[~2019-12-12 22:35 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-12 22:35 Waiman Long [this message]
2019-12-12 22:35 ` [PATCH 1/5] locking/lockdep: Track number of zapped classes Waiman Long
2019-12-12 22:35 ` [PATCH 2/5] locking/lockdep: Track leaked chain_hlocks entries Waiman Long
2019-12-12 22:35 ` [PATCH 3/5] locking/lockdep: Track number of zapped lock chains Waiman Long
2019-12-12 22:35 ` [PATCH 4/5] locking/lockdep: Reuse free chain_hlocks entries Waiman Long
2019-12-13 10:25   ` Peter Zijlstra
2019-12-13 10:50     ` Peter Zijlstra
2019-12-13 16:02       ` Waiman Long
2019-12-13 16:05         ` Waiman Long
2019-12-13 18:12         ` Peter Zijlstra
     [not found]           ` <7ca26a9a-003f-6f24-08e4-f01b80e3e962@redhat.com>
2019-12-13 18:47             ` Peter Zijlstra
2019-12-13 20:08               ` Waiman Long
2019-12-15 17:06                 ` Waiman Long
2019-12-13 15:02     ` Waiman Long
2019-12-13 18:43     ` Peter Zijlstra
2019-12-12 22:35 ` [PATCH 5/5] locking/lockdep: Decrement irq context counters when removing lock chain Waiman Long

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