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authorPeter Zijlstra <peterz@infradead.org>2018-01-10 19:23:08 +0100
committerIngo Molnar <mingo@kernel.org>2018-01-25 14:48:30 +0100
commitefe951d3de9141626a494bcb1efb0650eaef6491 (patch)
tree700b1669ac70b2fb6ddc854ac931e2cc6c8b0105
parentperf/core: Fix ctx::mutex deadlock (diff)
downloadlinux-efe951d3de9141626a494bcb1efb0650eaef6491.tar.xz
linux-efe951d3de9141626a494bcb1efb0650eaef6491.zip
perf/x86: Fix perf,x86,cpuhp deadlock
More lockdep gifts, a 5-way lockup race: perf_event_create_kernel_counter() perf_event_alloc() perf_try_init_event() x86_pmu_event_init() __x86_pmu_event_init() x86_reserve_hardware() #0 mutex_lock(&pmc_reserve_mutex); reserve_ds_buffer() #1 get_online_cpus() perf_event_release_kernel() _free_event() hw_perf_event_destroy() x86_release_hardware() #0 mutex_lock(&pmc_reserve_mutex) release_ds_buffer() #1 get_online_cpus() #1 do_cpu_up() perf_event_init_cpu() #2 mutex_lock(&pmus_lock) #3 mutex_lock(&ctx->mutex) sys_perf_event_open() mutex_lock_double() #3 mutex_lock(ctx->mutex) #4 mutex_lock_nested(ctx->mutex, 1); perf_try_init_event() #4 mutex_lock_nested(ctx->mutex, 1) x86_pmu_event_init() intel_pmu_hw_config() x86_add_exclusive() #0 mutex_lock(&pmc_reserve_mutex) Fix it by using ordering constructs instead of locking. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/events/intel/ds.c33
1 files changed, 18 insertions, 15 deletions
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 8156e47da7ba..18c25ab28557 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -372,10 +372,9 @@ static int alloc_pebs_buffer(int cpu)
static void release_pebs_buffer(int cpu)
{
struct cpu_hw_events *hwev = per_cpu_ptr(&cpu_hw_events, cpu);
- struct debug_store *ds = hwev->ds;
void *cea;
- if (!ds || !x86_pmu.pebs)
+ if (!x86_pmu.pebs)
return;
kfree(per_cpu(insn_buffer, cpu));
@@ -384,7 +383,6 @@ static void release_pebs_buffer(int cpu)
/* Clear the fixmap */
cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers.pebs_buffer;
ds_clear_cea(cea, x86_pmu.pebs_buffer_size);
- ds->pebs_buffer_base = 0;
dsfree_pages(hwev->ds_pebs_vaddr, x86_pmu.pebs_buffer_size);
hwev->ds_pebs_vaddr = NULL;
}
@@ -419,16 +417,14 @@ static int alloc_bts_buffer(int cpu)
static void release_bts_buffer(int cpu)
{
struct cpu_hw_events *hwev = per_cpu_ptr(&cpu_hw_events, cpu);
- struct debug_store *ds = hwev->ds;
void *cea;
- if (!ds || !x86_pmu.bts)
+ if (!x86_pmu.bts)
return;
/* Clear the fixmap */
cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers.bts_buffer;
ds_clear_cea(cea, BTS_BUFFER_SIZE);
- ds->bts_buffer_base = 0;
dsfree_pages(hwev->ds_bts_vaddr, BTS_BUFFER_SIZE);
hwev->ds_bts_vaddr = NULL;
}
@@ -454,16 +450,22 @@ void release_ds_buffers(void)
if (!x86_pmu.bts && !x86_pmu.pebs)
return;
- get_online_cpus();
- for_each_online_cpu(cpu)
+ for_each_possible_cpu(cpu)
+ release_ds_buffer(cpu);
+
+ for_each_possible_cpu(cpu) {
+ /*
+ * Again, ignore errors from offline CPUs, they will no longer
+ * observe cpu_hw_events.ds and not program the DS_AREA when
+ * they come up.
+ */
fini_debug_store_on_cpu(cpu);
+ }
for_each_possible_cpu(cpu) {
release_pebs_buffer(cpu);
release_bts_buffer(cpu);
- release_ds_buffer(cpu);
}
- put_online_cpus();
}
void reserve_ds_buffers(void)
@@ -483,8 +485,6 @@ void reserve_ds_buffers(void)
if (!x86_pmu.pebs)
pebs_err = 1;
- get_online_cpus();
-
for_each_possible_cpu(cpu) {
if (alloc_ds_buffer(cpu)) {
bts_err = 1;
@@ -521,11 +521,14 @@ void reserve_ds_buffers(void)
if (x86_pmu.pebs && !pebs_err)
x86_pmu.pebs_active = 1;
- for_each_online_cpu(cpu)
+ for_each_possible_cpu(cpu) {
+ /*
+ * Ignores wrmsr_on_cpu() errors for offline CPUs they
+ * will get this call through intel_pmu_cpu_starting().
+ */
init_debug_store_on_cpu(cpu);
+ }
}
-
- put_online_cpus();
}
/*