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    SubjectRe: [PATCH v2 0/6] locking/lockdep: Reuse zapped chain_hlocks entries
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    On 12/16/19 10:15 AM, Waiman Long wrote:
    > v2:
    > - Revamp the chain_hlocks reuse patch to store the freed chain_hlocks
    > information in the chain_hlocks entries themselves avoiding the
    > need of a separate set of tracking structures. This, however,
    > requires a minimum allocation size of at least 2. Thanks to PeterZ
    > for his review and inspiring this change.
    > - Remove the leakage counter as it is no longer applicable.
    > - Add patch 6 to make the output of /proc/lockdep_chains more readable.
    >
    > It was found that when running a workload that kept on adding lock
    > classes and then zapping them repetitively, the system will eventually
    > run 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
    > and makes the output of /proc/lockdep_chains more readable.
    >
    > Waiman Long (6):
    > locking/lockdep: Track number of zapped classes
    > locking/lockdep: Throw away all lock chains with zapped class
    > locking/lockdep: Track number of zapped lock chains
    > locking/lockdep: Reuse freed chain_hlocks entries
    > locking/lockdep: Decrement irq context counters when removing lock
    > chain
    > locking/lockdep: Display irq_context names in /proc/lockdep_chains
    >
    > kernel/locking/lockdep.c | 307 +++++++++++++++++++++++------
    > kernel/locking/lockdep_internals.h | 14 +-
    > kernel/locking/lockdep_proc.c | 26 ++-
    > 3 files changed, 282 insertions(+), 65 deletions(-)
    >
    Ping! Any comments or suggestion for further improvement?

    Cheers,
    Longman

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