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 5D6BB39448F; Sat, 12 Sep 2026 07:12:10 +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=1789197131; cv=none; b=X2GtrcLjgHIg8Ag8YPxfMD7IjgJ7Ql/3aZlzZ3QxLs77+uYxSEenfgxVTP+y/fQ9ii1OGmniaioo6XH3qet9y21bR0faeDOTq525mdyjheIuLkOwCrV6j9jIB4dwhxfm5dCuGhJMgWrI5kw8rWXo15Y9PU35F4zh65Nt00MaEFo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789197131; c=relaxed/simple; bh=2fpKPkL3iP3I1ABTNQVaBumtZyZZMgYVfkQ3OGpdbWM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cy8puZ6UDKv7UCRo74ReG6r86W2yvPhCteULULaVf7Jc0ODE1yNuf6Oq/TuNhF47ovS04N+VCp0vjD83tFhFnOd64GeZpgsG/sYd5UKtJ/il2jeVGGeU2JSptLbOEKmRk5Ft4Sw4B4CYZjdQ+XyeWbFJ3d4wTXbhj5PHv5Z0Kig= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=lvzueA7z; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="lvzueA7z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 135101F000FF; Sat, 12 Sep 2026 07:12:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789197130; bh=SYnqS42avlp5p9f+VnuO+WNv9cwVfjIuGyP9bfPUZ1E=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=lvzueA7zuStxIO6lEofXg8zJwz7jKftNVxgwy3UFzL8mskbnbCyf6pv1NX/9BPRfe TH9rJjNIEjCOUHIAPvxy2WIVt4l+CoMOdDqV9Oo0nSeS2pPu8h/kYe6VD0oowcF1T9 /7VDZCpzEnIWfs69HJbTGUgBgaGJVZq8hWjtSrJo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zide Chen , "Peter Zijlstra (Intel)" , Ian Rogers , Dapeng Mi , Sasha Levin Subject: [PATCH 7.2 0108/1815] perf/x86/intel/uncore: Fix uncore_box ref/unref ordering Date: Sat, 12 Sep 2026 08:30:58 +0200 Message-ID: <20260912065651.541798965@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065648.999753832@linuxfoundation.org> References: <20260912065648.999753832@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zide Chen [ Upstream commit 174f0582e38abe03b88e15f04bfe58490f88cb19 ] In uncore_event_cpu_online(), uncore_box_ref() was called before uncore_change_context(). uncore_box_ref() gates on box->cpu >= 0, but box->cpu is still -1 at that point because uncore_change_context() has not run yet. As a result, the box is never initialized on the first CPU to come online in a die, leaving it permanently uninitialized in the single-CPU-per-die case. Thus, box->refcnt is one count below the true value, and in the CPU offline path, the box will be torn down on the second-to-last CPU. In uncore_event_cpu_offline(), uncore_box_unref() was called after uncore_change_context(), so box->cpu is already -1 when the collector CPU goes offline, which prevents it from tearing down the box. Fix by swapping the call order in both paths so that uncore_box_{ref,unref}() runs at the point where box->cpu reflects the correct context. Move allocate_boxes() out of uncore_box_ref() to enable this reordering. Fixes: c74443d92f68 ("perf/x86/uncore: Support per PMU cpumask") Signed-off-by: Zide Chen Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ian Rogers Reviewed-by: Dapeng Mi Link: https://patch.msgid.link/20260611160033.66760-8-zide.chen@intel.com Signed-off-by: Sasha Levin --- arch/x86/events/intel/uncore.c | 50 ++++++++++++++++------------------ 1 file changed, 23 insertions(+), 27 deletions(-) diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c index feb8c3b0076b2..b9ac2f7d31caa 100644 --- a/arch/x86/events/intel/uncore.c +++ b/arch/x86/events/intel/uncore.c @@ -1580,9 +1580,15 @@ static int uncore_event_cpu_offline(unsigned int cpu) { int die, target; + /* Clear the references */ + die = topology_logical_die_id(cpu); + uncore_box_unref(uncore_msr_uncores, die); + uncore_box_unref(uncore_mmio_uncores, die); + /* Check if exiting cpu is used for collecting uncore events */ if (!cpumask_test_and_clear_cpu(cpu, &uncore_cpu_mask)) - goto unref; + return 0; + /* Find a new cpu to collect uncore events */ target = cpumask_any_but(topology_die_cpumask(cpu), cpu); @@ -1595,16 +1601,10 @@ static int uncore_event_cpu_offline(unsigned int cpu) uncore_change_context(uncore_msr_uncores, cpu, target); uncore_change_context(uncore_mmio_uncores, cpu, target); uncore_change_context(uncore_pci_uncores, cpu, target); - -unref: - /* Clear the references */ - die = topology_logical_die_id(cpu); - uncore_box_unref(uncore_msr_uncores, die); - uncore_box_unref(uncore_mmio_uncores, die); return 0; } -static int allocate_boxes(struct intel_uncore_type **types, +static void allocate_boxes(struct intel_uncore_type **types, unsigned int die, unsigned int cpu) { struct intel_uncore_box *box, *tmp; @@ -1621,8 +1621,10 @@ static int allocate_boxes(struct intel_uncore_type **types, if (pmu->boxes[die] || uncore_pmu_broken(pmu)) continue; box = uncore_alloc_box(type, cpu_to_node(cpu)); - if (!box) + if (!box) { + uncore_pmu_set_broken(pmu); goto cleanup; + } box->pmu = pmu; box->dieid = die; list_add(&box->active_list, &allocated); @@ -1633,14 +1635,13 @@ static int allocate_boxes(struct intel_uncore_type **types, list_del_init(&box->active_list); box->pmu->boxes[die] = box; } - return 0; + return; cleanup: list_for_each_entry_safe(box, tmp, &allocated, active_list) { list_del_init(&box->active_list); kfree(box); } - return -ENOMEM; } static int uncore_box_ref(struct intel_uncore_type **types, @@ -1649,11 +1650,7 @@ static int uncore_box_ref(struct intel_uncore_type **types, struct intel_uncore_type *type; struct intel_uncore_pmu *pmu; struct intel_uncore_box *box; - int i, ret; - - ret = allocate_boxes(types, die, cpu); - if (ret) - return ret; + int i; for (; *types; types++) { type = *types; @@ -1669,27 +1666,26 @@ static int uncore_box_ref(struct intel_uncore_type **types, static int uncore_event_cpu_online(unsigned int cpu) { - int die, target, msr_ret, mmio_ret; + int die, target; die = topology_logical_die_id(cpu); - msr_ret = uncore_box_ref(uncore_msr_uncores, die, cpu); - mmio_ret = uncore_box_ref(uncore_mmio_uncores, die, cpu); + allocate_boxes(uncore_msr_uncores, die, cpu); + allocate_boxes(uncore_mmio_uncores, die, cpu); /* * Check if there is an online cpu in the package * which collects uncore events already. */ target = cpumask_any_and(&uncore_cpu_mask, topology_die_cpumask(cpu)); - if (target < nr_cpu_ids) - return 0; - - cpumask_set_cpu(cpu, &uncore_cpu_mask); - - if (!msr_ret) + if (target >= nr_cpu_ids) { + cpumask_set_cpu(cpu, &uncore_cpu_mask); uncore_change_context(uncore_msr_uncores, -1, cpu); - if (!mmio_ret) uncore_change_context(uncore_mmio_uncores, -1, cpu); - uncore_change_context(uncore_pci_uncores, -1, cpu); + uncore_change_context(uncore_pci_uncores, -1, cpu); + } + + uncore_box_ref(uncore_msr_uncores, die, cpu); + uncore_box_ref(uncore_mmio_uncores, die, cpu); return 0; } -- 2.53.0