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    SubjectRe: [PATCH] lockup_detector: Make DETECT_HUNT_TASK default depend on LOCKUP_DETECTOR

    * Frederic Weisbecker <fweisbec@gmail.com> wrote:

    > > The thing is, CONFIG_DETECT_SOFTLOCKUP was default-y before, so many
    > > people had it enabled [and had it forced-enabled if DEBUG_KERNEL was off],
    > > even if they didnt really want or need it.
    >
    > Hmm. It was:
    >
    > config DETECT_SOFTLOCKUP
    > bool "Detect Soft Lockups"
    > depends on DEBUG_KERNEL && !S390
    > default y
    >
    > It means it's default enabled only if DEBUG_KERNEL, right? Then if you don't
    > select CONFIG_DEBUG_KERNEL, it's fine as it won't be selected.

    Indeed, you are right.

    Anyway, i think the general point remains: i'm not sure we should
    default-enable this feature.

    > But I agree with you. There is a bunch of config options for which selection
    > is a duty when you are a kernel developer: PROVE_LOCKING, DETECT_HUNG_TASK,
    > DEBUG_PREEMPT, PROVE_RCU, etc... Because they all show (or prove we can
    > have) bugs that one might miss without these options. Softlockups are rarely
    > part of them because even without the lockup detector enabled, you'll
    > observe something is wrong.

    Note that it's now detecting all kinds of lockups: softlockups, hard lockups
    and even unkillable hung tasks.

    Ingo


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