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([2a09:bac1:76a0:540::22d:10b]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7bf43028b5esm4807403a34.25.2025.10.07.09.46.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Oct 2025 09:46:28 -0700 (PDT) From: Chris J Arges To: stable@vger.kernel.org Cc: kernel-team@cloudflare.com, Peter Zijlstra , David Wang <00107082@163.com>, Yeoreum Yun , Chris J Arges Subject: [PATCH] perf: Fix dangling cgroup pointer in cpuctx Date: Tue, 7 Oct 2025 11:45:52 -0500 Message-ID: <20251007164556.516406-1-carges@cloudflare.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Yeoreum Yun [ Upstream commit 3b7a34aebbdf2a4b7295205bf0c654294283ec82 ] Commit a3c3c66670ce ("perf/core: Fix child_total_time_enabled accounting bug at task exit") moves the event->state update to before list_del_event(). This makes the event->state test in list_del_event() always false; never calling perf_cgroup_event_disable(). As a result, cpuctx->cgrp won't be cleared properly; causing havoc. Cc: stable@vger.kernel.org # 6.6.x, 6.12.x Fixes: a3c3c66670ce ("perf/core: Fix child_total_time_enabled accounting bug at task exit") Signed-off-by: Chris J Arges --- kernel/events/core.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 3cc06ffb60c1..6688660845d2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2100,18 +2100,6 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) if (event->group_leader == event) del_event_from_groups(event, ctx); - /* - * If event was in error state, then keep it - * that way, otherwise bogus counts will be - * returned on read(). The only way to get out - * of error state is by explicit re-enabling - * of the event - */ - if (event->state > PERF_EVENT_STATE_OFF) { - perf_cgroup_event_disable(event, ctx); - perf_event_set_state(event, PERF_EVENT_STATE_OFF); - } - ctx->generation++; event->pmu_ctx->nr_events--; } @@ -2456,11 +2444,14 @@ __perf_remove_from_context(struct perf_event *event, */ if (flags & DETACH_EXIT) state = PERF_EVENT_STATE_EXIT; - if (flags & DETACH_DEAD) { - event->pending_disable = 1; + if (flags & DETACH_DEAD) state = PERF_EVENT_STATE_DEAD; - } + event_sched_out(event, ctx); + + if (event->state > PERF_EVENT_STATE_OFF) + perf_cgroup_event_disable(event, ctx); + perf_event_set_state(event, min(event->state, state)); if (flags & DETACH_GROUP) perf_group_detach(event); -- 2.43.0