Commit-ID: efe951d3de9141626a494bcb1efb0650eaef6491
Gitweb: https://git.kernel.org/tip/efe951d3de9141626a494bcb1efb0650eaef6491
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 10 Jan 2018 19:23:08 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 25 Jan 2018 14:48:30 +0100
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@xxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/events/intel/ds.c | 33 ++++++++++++++++++---------------
1 file changed, 18 insertions(+), 15 deletions(-)
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 8156e47..18c25ab 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();
}
/*
--
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