Re: [PATCH v2] perf stat: Fix crash on arm64

Ian Rogers
2026-03-25T22:27:18Z

On Wed, Mar 25, 2026 at 1:59 PM Leo Yan <leo.yan@arm.com> wrote:
>
> On Wed, Mar 25, 2026 at 03:24:30AM -0700, 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")
> > Tested-by: Dmitry Ilvokhin <d@ilvokhin.com>
> > Signed-off-by: Breno Leitao <leitao@debian.org>
>
> As Arnaldo mentioned in v1, I also found Segmentation fault when
> testing this patch:
>
> Program received signal SIGSEGV, Segmentation fault.
> metricgroup__copy_metric_events (evlist=0xaaaaab037750, cgrp=0x0, new_metric_events=0xaaaaab038210, old_metric_events=0xaaaaab038d20) at util/metricgroup.c:1662
> 1662 evsel = evlist__find_evsel(evlist, old_me->evsel->core.idx);
> (gdb) bt
> #0 metricgroup__copy_metric_events (evlist=0xaaaaab037750, cgrp=0x0, new_metric_events=0xaaaaab038210, old_metric_events=0xaaaaab038d20) at util/metricgroup.c:1662
> #1 0x0000aaaaaab05870 in add_default_events () at builtin-stat.c:2110
> #2 0x0000aaaaaab08300 in cmd_stat (argc=0, argv=0xfffffffffaa0) at builtin-stat.c:2838
> #3 0x0000aaaaaab40998 in run_builtin (p=0xaaaaaaf9d428 <commands+360>, argc=4, argv=0xfffffffffaa0) at perf.c:348
> #4 0x0000aaaaaab40c14 in handle_internal_command (argc=4, argv=0xfffffffffaa0) at perf.c:398
> #5 0x0000aaaaaab40ddc in run_argv (argcp=0xfffffffff8bc, argv=0xfffffffff8b0) at perf.c:442
> #6 0x0000aaaaaab41110 in main (argc=4, argv=0xfffffffffaa0) at perf.c:549
>
> Last week I tested v1 and confirmed the issue was gone with the change,
> I will dig a bit in tomorrow and share back if any finding.
>
> Apologies for my lazy, as I should double check once Arnaldo
> pointed out in v1.

From the stack trace I don't see anything that should allow this.
Either the list of metrics is broken, or the struct metric_event's
evsel is NULL. But that should never happen as we wouldn't have a
metric at that point. The sorting shouldn't affect that. If you can
reproduce the issue, verbose logs may help.

Thanks,
Ian

> Thanks,
> Leo