From nobody Thu Dec 18 08:35:40 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C5B1426656E; Mon, 24 Feb 2025 18:36:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740422204; cv=none; b=uTCZZkmWymeyCXu6Kkb4BgcpNekNYyugHClOXQnRHJVvQIRFk6mjKa7drpBgttK1jcs9IcVeZSw4jMlVGQPHrpk4qVdlVBegQuapatlALcrHL5X6kxzI9LD3nuvoCj8txRCerPVFMlZI30PjNhx5q+1623lCbzXPhVTHGUtmXow= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740422204; c=relaxed/simple; bh=M4VPRT6o6MozbN+TH3tx4tc7aWbSW58mgJKcuBKG6ZM=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=mu68BpwgGWW1ckx8HZ7PoPq0hA+ukAzP9wUuUNxmvVZkDxdVw0HbE7lgLXmSdEZYHwbwRfVixTLs5rSOT+Q9BacYLI6Zm8nFB6yZwbI6BuaoD0N3vh11sHq1Fo35AHnxllbw/ml9ZjeKieOUzcmraWiu39GQjoxIBlTmtNif1vg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=fbhJmzOW; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=CWX7kvZj; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="fbhJmzOW"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="CWX7kvZj" Date: Mon, 24 Feb 2025 18:36:34 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1740422198; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QiAFBPY73VaBh9CvFiz4PNXDthwdrgK2k3EDjPxurSg=; b=fbhJmzOWqh+C4Zde9yXFZv/HUyy0yNxedH0MVNFVRLaNTFWPFXTGKOBGLLqYwhMgD6mQSG LbYHATE10L9eX5ITRJNp/mfDLTKBOUyuS6kobFZ9+LFA20BtsPD7Eqw8Ut5szF7HuLtvGS zWq14IvuzrUcyC2nAUrc+LITL8/INT+54LlfXzHqURX+ijkF25tBn3ajnlBUkF2jEFnMzW D561NTJHOIneL7HhXNN5zma1+Vg3dFxx20wgrm5etzwgIUDdEghDyadqKFQU2wwsAhITqp vdKaJ4OsfGeWBA5gt21bzcchk+4aGoIR5N0H2I3rWbsXyEZjgkY/+gFpy/Uoxg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1740422198; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QiAFBPY73VaBh9CvFiz4PNXDthwdrgK2k3EDjPxurSg=; b=CWX7kvZjzF+SlOw55sV00Q3Qxs6kAh6RBxLByNcBarcjqlNTqeuGYGL5IbZ36QU9QhN0Xg 2M89ZeiErMiCqQDQ== From: "tip-bot2 for Luo Gengkun" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/urgent] perf/core: Order the PMU list to fix warning about unordered pmu_ctx_list Cc: Luo Gengkun , Ingo Molnar , Kan Liang , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250122073356.1824736-1-luogengkun@huaweicloud.com> References: <20250122073356.1824736-1-luogengkun@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174042219525.10177.4368075939520286235.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the perf/urgent branch of tip: Commit-ID: 2016066c66192a99d9e0ebf433789c490a6785a2 Gitweb: https://git.kernel.org/tip/2016066c66192a99d9e0ebf433789c490= a6785a2 Author: Luo Gengkun AuthorDate: Wed, 22 Jan 2025 07:33:56=20 Committer: Ingo Molnar CommitterDate: Mon, 24 Feb 2025 19:22:37 +01:00 perf/core: Order the PMU list to fix warning about unordered pmu_ctx_list Syskaller triggers a warning due to prev_epc->pmu !=3D next_epc->pmu in perf_event_swap_task_ctx_data(). vmcore shows that two lists have the same perf_event_pmu_context, but not in the same order. The problem is that the order of pmu_ctx_list for the parent is impacted by the time when an event/PMU is added. While the order for a child is impacted by the event order in the pinned_groups and flexible_groups. So the order of pmu_ctx_list in the parent and child may be different. To fix this problem, insert the perf_event_pmu_context to its proper place after iteration of the pmu_ctx_list. The follow testcase can trigger above warning: # perf record -e cycles --call-graph lbr -- taskset -c 3 ./a.out & # perf stat -e cpu-clock,cs -p xxx // xxx is the pid of a.out test.c void main() { int count =3D 0; pid_t pid; printf("%d running\n", getpid()); sleep(30); printf("running\n"); pid =3D fork(); if (pid =3D=3D -1) { printf("fork error\n"); return; } if (pid =3D=3D 0) { while (1) { count++; } } else { while (1) { count++; } } } The testcase first opens an LBR event, so it will allocate task_ctx_data, and then open tracepoint and software events, so the parent context will have 3 different perf_event_pmu_contexts. On inheritance, child ctx will insert the perf_event_pmu_context in another order and the warning will trigger. [ mingo: Tidied up the changelog. ] Fixes: bd2756811766 ("perf: Rewrite core context handling") Signed-off-by: Luo Gengkun Signed-off-by: Ingo Molnar Reviewed-by: Kan Liang Link: https://lore.kernel.org/r/20250122073356.1824736-1-luogengkun@huaweic= loud.com --- kernel/events/core.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 7dabbca..086d46d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4950,7 +4950,7 @@ static struct perf_event_pmu_context * find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx, struct perf_event *event) { - struct perf_event_pmu_context *new =3D NULL, *epc; + struct perf_event_pmu_context *new =3D NULL, *pos =3D NULL, *epc; void *task_ctx_data =3D NULL; =20 if (!ctx->task) { @@ -5007,12 +5007,19 @@ find_get_pmu_context(struct pmu *pmu, struct perf_e= vent_context *ctx, atomic_inc(&epc->refcount); goto found_epc; } + /* Make sure the pmu_ctx_list is sorted by PMU type: */ + if (!pos && epc->pmu->type > pmu->type) + pos =3D epc; } =20 epc =3D new; new =3D NULL; =20 - list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list); + if (!pos) + list_add_tail(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list); + else + list_add(&epc->pmu_ctx_entry, pos->pmu_ctx_entry.prev); + epc->ctx =3D ctx; =20 found_epc: