From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6D4E14968FA; Wed, 29 Jul 2026 14:56:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785336970; cv=none; b=SkmR681crqf3IgMin0xr1JZPHfIeWvqz3CzzsuzXhuxTW0++UjI2cduFwlcBTOp4IemgGgNGHyg++JxVpVih/Zn3aAbZaoZ1GYLRj+sdDVP/MHDSBN6xwXmqH4e8uduFLBNiml4tEYxQjJV1HjnZWgqiktO40GgUDNMb1yEI83I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785336970; c=relaxed/simple; bh=90W4mubrGLPUrU0fzf0gWDn/muhXdeozbxjssJTaQ2k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nbdY8Fodl7IjxpawExK8tMSdWDtp9P1ZEJ2fXp8o2pdU0+NjzQ1AQ7j/pwb6FWsfYF0yw2FFesQgeCe6jdp2/QMrS1gcNx4kiJ3UWS1//McQCrAN0DUQM2ITw/KBiZrW50PZo9CM8YOYu925ND6+/YPbwX4qFI80Qd41qoiAjSs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1EBEC1F000E9; Wed, 29 Jul 2026 14:56:09 +0000 (UTC) From: Dave Jiang To: linux-cxl@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: jic23@kernel.org, will@kernel.org, mark.rutland@arm.com, dave@stgolabs.net, sashiko-bot@kernel.org Subject: [PATCH v2 8/9] perf/cxl: Don't use pmu.dev in IRQ and hotplug callbacks after unregister Date: Wed, 29 Jul 2026 07:55:54 -0700 Message-ID: <20260729145555.3919550-9-dave.jiang@intel.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260729145555.3919550-1-dave.jiang@intel.com> References: <20260729145555.3919550-1-dave.jiang@intel.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On device removal the devm actions unwind LIFO, so cxl_pmu_perf_unregister() runs first and perf_pmu_unregister() frees info->pmu.dev (device_del() + put_device() -> kfree()). The overflow IRQ (freed last) and the CPU-hotplug instance (removed next) are still live at that point, and both cxl_pmu_irq() and cxl_pmu_offline_cpu() log via dev_dbg()/dev_err() on info->pmu.dev, dereferencing freed memory. The shared IRQ can be entered for a co-function on the same MSI vector, and a CPU can go offline in the window before the hotplug instance is removed. Log through info->pmu.parent instead, the cxl_pmu device passed to probe, which is devm-managed and outlives every teardown action. Fixes: 5d7107c72796 ("perf: CXL Performance Monitoring Unit driver") Reported-by: sashiko-bot@kernel.org Closes: https://sashiko.dev/#/patchset/20260715191454.459673-1-dave@stgolabs.net?part=1 Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Dave Jiang --- drivers/perf/cxl_pmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/perf/cxl_pmu.c b/drivers/perf/cxl_pmu.c index 2e817a52ff1e..f42238b2b6b0 100644 --- a/drivers/perf/cxl_pmu.c +++ b/drivers/perf/cxl_pmu.c @@ -803,7 +803,7 @@ static irqreturn_t cxl_pmu_irq(int irq, void *data) struct perf_event *event = info->hw_events[i]; if (!event) { - dev_dbg(info->pmu.dev, + dev_dbg(info->pmu.parent, "overflow but on non enabled counter %d\n", i); continue; } @@ -966,7 +966,7 @@ static int cxl_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) info->on_cpu = -1; target = cpumask_any_but(cpu_online_mask, cpu); if (target >= nr_cpu_ids) { - dev_err(info->pmu.dev, "Unable to find a suitable CPU\n"); + dev_err(info->pmu.parent, "Unable to find a suitable CPU\n"); return 0; } -- 2.55.0