rapl_cpu_prepare() must be called after logical package id of CPU
is set by topology_update_package_map().
But when onlining hot-added CPU, rapl_cpu_prepare() is called before
setting logical package id of the hot-added CPU. So cpu_to_rapl_pmu()
in rapl_cpu_prepare() finds a rapl_pmu of wrong logical package id and
rapl_cpu_prepare() initializes the wrong rapl_pmu.
After that logical package id of the hot-added CPU is set by
topology_update_package_map(). But rapl_cpu_prepare() does
not initialize pmu of the logical package id of the hot-added CPU.
So when calling rapl_cpu_online(), cpu_to_rapl_pmu() returns NULL and
the following NULL pointer dereference occurs.
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: rapl_cpu_online+0x8d/0xb0
<snip>
Call Trace:
? rapl_cpu_offline+0xc0/0xc0
cpuhp_invoke_callback+0x8d/0x3f0
cpuhp_up_callbacks+0x37/0xb0
cpuhp_thread_fun+0xc9/0xe0
smpboot_thread_fn+0x110/0x160
kthread+0x101/0x140
? sort_range+0x30/0x30
? kthread_park+0x90/0x90
ret_from_fork+0x25/0x30
The patch renames rapl_cpu_prepare() to rapl_cpu_starting() and changes
the position of cpuhp_state so that rapl_cpu_starting() is called
after topology_update_package_map().
Fixes: 9de8d686955b ("perf/x86/intel/rapl: Convert it to a per package
facility")
Signed-off-by: Yasuaki Ishimatsu <[email protected]>
CC: Thomas Gleixner <[email protected]>
---
arch/x86/events/intel/rapl.c | 11 ++++++-----
include/linux/cpuhotplug.h | 2 +-
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/events/intel/rapl.c b/arch/x86/events/intel/rapl.c
index 17c3564..f762cd6 100644
--- a/arch/x86/events/intel/rapl.c
+++ b/arch/x86/events/intel/rapl.c
@@ -598,7 +598,7 @@ static int rapl_cpu_online(unsigned int cpu)
return 0;
}
-static int rapl_cpu_prepare(unsigned int cpu)
+static int rapl_cpu_starting(unsigned int cpu)
{
struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
@@ -804,8 +804,9 @@ static int __init rapl_pmu_init(void)
* Install callbacks. Core will call them for each online cpu.
*/
- ret = cpuhp_setup_state(CPUHP_PERF_X86_RAPL_PREP,
"perf/x86/rapl:prepare",
- rapl_cpu_prepare, NULL);
+ ret = cpuhp_setup_state(CPUHP_AP_PERF_X86_RAPL_STARTING,
+ "perf/x86/rapl:starting",
+ rapl_cpu_starting, NULL);
if (ret)
goto out;
@@ -825,7 +826,7 @@ static int __init rapl_pmu_init(void)
out2:
cpuhp_remove_state(CPUHP_AP_PERF_X86_RAPL_ONLINE);
out1:
- cpuhp_remove_state(CPUHP_PERF_X86_RAPL_PREP);
+ cpuhp_remove_state(CPUHP_AP_PERF_X86_RAPL_STARTING);
out:
pr_warn("Initialization failed (%d), disabled\n", ret);
cleanup_rapl_pmus();
@@ -836,7 +837,7 @@ static int __init rapl_pmu_init(void)
static void __exit intel_rapl_exit(void)
{
cpuhp_remove_state_nocalls(CPUHP_AP_PERF_X86_RAPL_ONLINE);
- cpuhp_remove_state_nocalls(CPUHP_PERF_X86_RAPL_PREP);
+ cpuhp_remove_state_nocalls(CPUHP_AP_PERF_X86_RAPL_STARTING);
perf_pmu_unregister(&rapl_pmus->pmu);
cleanup_rapl_pmus();
}
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index d936a00..63da322 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -10,7 +10,6 @@ enum cpuhp_state {
CPUHP_PERF_X86_PREPARE,
CPUHP_PERF_X86_UNCORE_PREP,
CPUHP_PERF_X86_AMD_UNCORE_PREP,
- CPUHP_PERF_X86_RAPL_PREP,
CPUHP_PERF_BFIN,
CPUHP_PERF_POWER,
CPUHP_PERF_SUPERH,
@@ -90,6 +89,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_X86_AMD_UNCORE_STARTING,
CPUHP_AP_PERF_X86_STARTING,
CPUHP_AP_PERF_X86_AMD_IBS_STARTING,
+ CPUHP_AP_PERF_X86_RAPL_STARTING,
CPUHP_AP_PERF_X86_CQM_STARTING,
CPUHP_AP_PERF_X86_CSTATE_STARTING,
CPUHP_AP_PERF_XTENSA_STARTING,
--
1.8.3.1
