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SubjectRe: [RFC PATCH 1/2] smp: Reduce logging due to dump_stack of CSD waiters.
On Sat, Apr 29, 2023 at 03:00:05AM +1000, Imran Khan wrote:
> If a waiter is waiting for CSD lock, its call stack will not change
> between first and subsequent hang detection for the same CSD lock.
> So dump_stack for the waiter only for first time detection.
>
> This avoids excessive logging on large scale systems(with hundreds
> of CPUs) where repetitive dump_stack from hundreds of CPUs can flood
> the console.
>
> Signed-off-by: Imran Khan <imran.f.khan@oracle.com>

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>

> ---
> kernel/smp.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/smp.c b/kernel/smp.c
> index ab3e5dad6cfe9..b7ccba677a0a0 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -248,7 +248,8 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *
> arch_send_call_function_single_ipi(cpu);
> }
> }
> - dump_stack();
> + if (firsttime)
> + dump_stack();
> *ts1 = ts2;
>
> return false;
> --
> 2.34.1
>

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