From: Zide Chen <zide.chen@intel.com> mainline inclusion from mainline-v7.3-rc1 commit 174f0582e38abe03b88e15f04bfe58490f88cb19 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18570 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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 <zide.chen@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ian Rogers <irogers@google.com> Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Link: https://patch.msgid.link/20260611160033.66760-8-zide.chen@intel.com Conflicts: arch/x86/events/intel/uncore.c [commit 30c0a1095652275768a5de67188ff888d1f5d190 not backport] Signed-off-by: Chen Yuxi <chenyuxi19@huawei.com> --- arch/x86/events/intel/uncore.c | 46 +++++++++++++++------------------- 1 file changed, 20 insertions(+), 26 deletions(-) diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c index 1784b296222b..ec7f457a48a7 100644 --- a/arch/x86/events/intel/uncore.c +++ b/arch/x86/events/intel/uncore.c @@ -1519,9 +1519,15 @@ 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); @@ -1534,16 +1540,10 @@ 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; @@ -1572,14 +1572,13 @@ 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, @@ -1588,11 +1587,7 @@ 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, id, cpu); - if (ret) - return ret; + int i; for (; *types; types++) { type = *types; @@ -1608,27 +1603,26 @@ 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; } -- 2.34.1