linux-kernel - [PATCH v2 0/2] debugobjects: Fix potential hard lockup by disabling lockdep

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Date:   Tue, 25 Sep 2018 10:41:07 -0400
From:   Waiman Long <longman@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will.deacon@....com>
Cc:     linux-kernel@...r.kernel.org,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        Arnd Bergmann <arnd@...db.de>, chuhu@...hat.com,
        Waiman Long <longman@...hat.com>
Subject: [PATCH v2 0/2] debugobjects: Fix potential hard lockup by disabling lockdep

 v2:
  - Add a lockdep patch to fix a dmesg warning message due to the use
    of the novalidate class.

The only locking used by the debugobjects code is just 2 sets of raw
spinlocks for synchronization purpose. When lockdep is enabled, the
locking operation itself will become much more expensive especially
if a number of locks have already been acquired previously. In some
extreme cases, it may lead to hard lockup.

As there isn't much value in debugging the debugobjects internal locks,
lockdep checking is now disabled for those internal locks. That will
speed up system operation without compromising the lock checking
operation of production code.

Waiman Long (2):
  locking/lockdep: Don't warn class/lock name mismatch for novalidate
    class
  debugobjects: Disable lockdep tracking of debugobjects internal locks

 kernel/locking/lockdep.c | 7 +++++--
 lib/debugobjects.c       | 9 ++++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

-- 
2.18.0