[PATCH] perf/x86/intel/cqm: Move WARN_ONs from intel_cqm_cpu_prepare to cqm_pick_event_reader

Yasuaki Ishimatsu
2015-08-11T20:31:09Z

When hot adding a CPU and onlining it, the following WARN_ON() messages
are shown:

[ 772.891448] ------------[ cut here ]------------
[ 772.896624] WARNING: CPU: 58 PID: 15169 at arch/x86/kernel/cpu/perf_event_intel_cqm.c:1268 intel_cqm_cpu_prepare+0x88/0x90()
[ 772.909167] Modules linked in:
[ 772.995134] CPU: 58 PID: 15169
[ 773.016633] 0000000000000000 0000000092fb60ed ffff88104febbba8 ffffffff8167b5fa
[ 773.024789] 0000000000000000 0000000000000000 ffff88104febbbe8 ffffffff810819ea
[ 773.033119] ffff88103be60000 ffff8c0fbc7ca020 ffffffff819fadf0 000000000000008f
[ 773.041461] Call Trace:
[ 773.044402] [<ffffffff8167b5fa>] dump_stack+0x45/0x57
[ 773.050160] [<ffffffff810819ea>] warn_slowpath_common+0x8a/0xc0
[ 773.056888] [<ffffffff81081b1a>] warn_slowpath_null+0x1a/0x20
[ 773.063426] [<ffffffff810365f8>] intel_cqm_cpu_prepare+0x88/0x90
[ 773.070253] [<ffffffff81036732>] intel_cqm_cpu_notifier+0x42/0x160
[ 773.077271] [<ffffffff810a0d3d>] notifier_call_chain+0x4d/0x80
[ 773.083901] [<ffffffff810a0e4e>] __raw_notifier_call_chain+0xe/0x10
[ 773.091007] [<ffffffff81081ef8>] _cpu_up+0xe8/0x190
[ 773.096555] [<ffffffff8108201a>] cpu_up+0x7a/0xa0
[ 773.101910] [<ffffffff816701b0>] cpu_subsys_online+0x40/0x90
[ 773.108332] [<ffffffff8143d777>] device_online+0x67/0x90
[ 773.114368] [<ffffffff8143d82a>] online_store+0x8a/0xa0
[ 773.120305] [<ffffffff8143aab8>] dev_attr_store+0x18/0x30
[ 773.126437] [<ffffffff8127224a>] sysfs_kf_write+0x3a/0x50
[ 773.132560] [<ffffffff812718d0>] kernfs_fop_write+0x120/0x170
[ 773.139078] [<ffffffff811f7657>] __vfs_write+0x37/0x100
[ 773.145019] [<ffffffff811fa398>] ? __sb_start_write+0x58/0x110
[ 773.151635] [<ffffffff8129d7ed>] ? security_file_permission+0x3d/0xc0
[ 773.158932] [<ffffffff811f7d59>] vfs_write+0xa9/0x190
[ 773.164674] [<ffffffff810234e6>] ? do_audit_syscall_entry+0x66/0x70
[ 773.171776] [<ffffffff811f8b55>] SyS_write+0x55/0xc0
[ 773.177423] [<ffffffff810672f0>] ? do_page_fault+0x30/0x80
[ 773.183654] [<ffffffff8168232e>] entry_SYSCALL_64_fastpath+0x12/0x71
[ 773.190843] ---[ end trace e6219d24386873bd ]---
[ 773.196573] smpboot: Booting Node 7 Processor 143 APIC 0x1f7
[ 773.221241] microcode: CPU143 sig=0x306f3, pf=0x80, revision=0x9
[ 773.228005] Will online and init hotplugged CPU: 143

Here is the root cause of the issue:
When calling intel_cqm_cpu_prepare() at CPU_UP_PREPARE notification,
the function checks that c86_chache_max_rmid is same as cqm_max_rmid
as follows:

static void intel_cqm_cpu_prepare(unsigned int cpu)
{
...
WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid);

But x86_cache_max_rmid of hot added CPU is not set yet, because it will
set in get_cpu_cap() which is called after CPU_UP_PREPARE notification.

So when onlining a hot added CPU, the WARN_ON() are always shown:

To fix the issue, the patch moves WARN_ON()s from intel_cqm_cpu_prepare() to
cqm_pick_event_reader() which is called at CPU_STARTING notification.

Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
CC: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikas Shivappa <vikas.shivappa@intel.com>
Cc: Kanaka Juvva <kanaka.d.juvva@intel.com>
CC: Matt Fleming <matt.fleming@intel.com>

---
arch/x86/kernel/cpu/perf_event_intel_cqm.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c
index 63eb68b..6196d3e 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c
@@ -1244,9 +1244,13 @@ static struct pmu intel_cqm_pmu = {

static inline void cqm_pick_event_reader(int cpu)
{
+ struct cpuinfo_x86 *c = &cpu_data(cpu);
int phys_id = topology_physical_package_id(cpu);
int i;

+ WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid);
+ WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale);
+
for_each_cpu(i, &cqm_cpumask) {
if (phys_id == topology_physical_package_id(i))
return; /* already got reader for this socket */
@@ -1258,14 +1262,10 @@ static inline void cqm_pick_event_reader(int cpu)
static void intel_cqm_cpu_prepare(unsigned int cpu)
{
struct intel_pqr_state *state = &per_cpu(pqr_state, cpu);
- struct cpuinfo_x86 *c = &cpu_data(cpu);

state->rmid = 0;
state->closid = 0;
state->rmid_usecnt = 0;
-
- WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid);
- WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale);
}

static void intel_cqm_cpu_exit(unsigned int cpu)
--
1.8.3.1