Re: [PATCH] perf stat: Fix crash on arm64

[Dmitry Ilvokhin <d@ilvokhin.com>]

On Thu, Feb 05, 2026 at 03:46:31AM -0800, Breno Leitao wrote:
> Perf stat is crashing on arm64 hosts with the following issue:
> 
> 	# make -C tools/perf DEBUG=1
> 	# perf stat sleep 1
> 	perf: util/evsel.c:2034: get_group_fd: Assertion `!(!leader->core.fd)' failed.
> 	[1]    1220794 IOT instruction (core dumped)  ./perf stat
> 
> The sorting function introduced by commit a745c0831c15c ("perf stat:
> Sort default events/metrics") compares events based on their individual
> properties. This can cause events from different groups to be
> interleaved, resulting in group members appearing before their leaders
> in the sorted evlist.
> 
> When the iterator opens events in list order, a group member may be
> processed before its leader has been opened.
> 
> For example, CPU_CYCLES (idx=32) with leader STALL_SLOT_BACKEND (idx=37)
> could be sorted before its leader, causing the crash when CPU_CYCLES
> tries to get its group fd from the not-yet-opened leader.
> 
> Fix this by comparing events based on their leader's attributes instead
> of their own attributes when the events are in different groups. This
> ensures all members of a group share the same sort key as their leader,
> keeping groups together and guaranteeing leaders are opened before their
> members.
> 
> Reported-by: Denis Yaroshevskiy <dyaroshev@meta.com>
> Fixes: a745c0831c15c ("perf stat: Sort default events/metrics")
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
> Cc; linux-arm-kernel@lists.infradead.org
> ---
>  tools/perf/builtin-stat.c | 26 +++++++++++++++++---------
>  1 file changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index ab40d85fb1259..3a423ca31d8d3 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -1938,25 +1938,33 @@ static int default_evlist_evsel_cmp(void *priv __maybe_unused,
>  	const struct evsel *lhs = container_of(lhs_core, struct evsel, core);
>  	const struct perf_evsel *rhs_core = container_of(r, struct perf_evsel, node);
>  	const struct evsel *rhs = container_of(rhs_core, struct evsel, core);
> +	const struct evsel *lhs_leader = evsel__leader(lhs);
> +	const struct evsel *rhs_leader = evsel__leader(rhs);
>  
> -	if (evsel__leader(lhs) == evsel__leader(rhs)) {
> +	if (lhs_leader == rhs_leader) {
>  		/* Within the same group, respect the original order. */
>  		return lhs_core->idx - rhs_core->idx;
>  	}
>  
> +	/*
> +	 * Compare using leader's attributes so that all members of a group
> +	 * stay together. This ensures leaders are opened before their members.
> +	 */
> +
>  	/* Sort default metrics evsels first, and default show events before those. */
> -	if (lhs->default_metricgroup != rhs->default_metricgroup)
> -		return lhs->default_metricgroup ? -1 : 1;
> +	if (lhs_leader->default_metricgroup != rhs_leader->default_metricgroup)
> +		return lhs_leader->default_metricgroup ? -1 : 1;
>  
> -	if (lhs->default_show_events != rhs->default_show_events)
> -		return lhs->default_show_events ? -1 : 1;
> +	if (lhs_leader->default_show_events != rhs_leader->default_show_events)
> +		return lhs_leader->default_show_events ? -1 : 1;
>  
>  	/* Sort by PMU type (prefers legacy types first). */
> -	if (lhs->pmu != rhs->pmu)
> -		return lhs->pmu->type - rhs->pmu->type;
> +	if (lhs_leader->pmu != rhs_leader->pmu)
> +		return lhs_leader->pmu->type - rhs_leader->pmu->type;
>  
> -	/* Sort by name. */
> -	return strcmp(evsel__name((struct evsel *)lhs), evsel__name((struct evsel *)rhs));
> +	/* Sort by leader's name. */
> +	return strcmp(evsel__name((struct evsel *)lhs_leader),
> +		      evsel__name((struct evsel *)rhs_leader));
>  }
>  
>  /*
> 
> ---
> base-commit: 5fd0a1df5d05ad066e5618ccdd3d0fa6cb686c27
> change-id: 20260205-perf_stat-a0a2a37e21c5
> 
> Best regards,
> --  
> Breno Leitao <leitao@debian.org>
> 

Tested-by: Dmitry Ilvokhin <d@ilvokhin.com>