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powerpc/imc-pmu: Fix use of mutex in IRQs disabled section

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Current imc-pmu code triggers a WARNING with CONFIG_DEBUG_ATOMIC_SLEEP
and CONFIG_PROVE_LOCKING enabled, while running a thread_imc event.

Command to trigger the warning:
  # perf stat -e thread_imc/CPM_CS_FROM_L4_MEM_X_DPTEG/ sleep 5

   Performance counter stats for 'sleep 5':

                   0      thread_imc/CPM_CS_FROM_L4_MEM_X_DPTEG/

         5.002117947 seconds time elapsed

         0.000131000 seconds user
         0.001063000 seconds sys

Below is snippet of the warning in dmesg:

  BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
  in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 2869, name: perf-exec
  preempt_count: 2, expected: 0
  4 locks held by perf-exec/2869:
   #0: c00000004325c540 (&sig->cred_guard_mutex){+.+.}-{3:3}, at: bprm_execve+0x64/0xa90
   #1: c00000004325c5d8 (&sig->exec_update_lock){++++}-{3:3}, at: begin_new_exec+0x460/0xef0
   #2: c0000003fa99d4e0 (&cpuctx_lock){-...}-{2:2}, at: perf_event_exec+0x290/0x510
   #3: c000000017ab8418 (&ctx->lock){....}-{2:2}, at: perf_event_exec+0x29c/0x510
  irq event stamp: 4806
  hardirqs last  enabled at (4805): [<c000000000f65b94>] _raw_spin_unlock_irqrestore+0x94/0xd0
  hardirqs last disabled at (4806): [<c0000000003fae44>] perf_event_exec+0x394/0x510
  softirqs last  enabled at (0): [<c00000000013c404>] copy_process+0xc34/0x1ff0
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  CPU: 36 PID: 2869 Comm: perf-exec Not tainted 6.2.0-rc2-00011-g1247637727f2 #61
  Hardware name: 8375-42A POWER9 0x4e1202 opal:v7.0-16-g9b85f7d961 PowerNV
  Call Trace:
    dump_stack_lvl+0x98/0xe0 (unreliable)
    __might_resched+0x2f8/0x310
    __mutex_lock+0x6c/0x13f0
    thread_imc_event_add+0xf4/0x1b0
    event_sched_in+0xe0/0x210
    merge_sched_in+0x1f0/0x600
    visit_groups_merge.isra.92.constprop.166+0x2bc/0x6c0
    ctx_flexible_sched_in+0xcc/0x140
    ctx_sched_in+0x20c/0x2a0
    ctx_resched+0x104/0x1c0
    perf_event_exec+0x340/0x510
    begin_new_exec+0x730/0xef0
    load_elf_binary+0x3f8/0x1e10
  ...
  do not call blocking ops when !TASK_RUNNING; state=2001 set at [<00000000fd63e7cf>] do_nanosleep+0x60/0x1a0
  WARNING: CPU: 36 PID: 2869 at kernel/sched/core.c:9912 __might_sleep+0x9c/0xb0
  CPU: 36 PID: 2869 Comm: sleep Tainted: G        W          6.2.0-rc2-00011-g1247637727f2 #61
  Hardware name: 8375-42A POWER9 0x4e1202 opal:v7.0-16-g9b85f7d961 PowerNV
  NIP:  c000000000194a1c LR: c000000000194a18 CTR: c000000000a78670
  REGS: c00000004d2134e0 TRAP: 0700   Tainted: G        W           (6.2.0-rc2-00011-g1247637727f2)
  MSR:  9000000000021033 <SF,HV,ME,IR,DR,RI,LE>  CR: 48002824  XER: 00000000
  CFAR: c00000000013fb64 IRQMASK: 1

The above warning triggered because the current imc-pmu code uses mutex
lock in interrupt disabled sections. The function mutex_lock()
internally calls __might_resched(), which will check if IRQs are
disabled and in case IRQs are disabled, it will trigger the warning.

Fix the issue by changing the mutex lock to spinlock.

Fixes: 8f95faaac5 ("powerpc/powernv: Detect and create IMC device")
Reported-by: Michael Petlan <mpetlan@redhat.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
[mpe: Fix comments, trim oops in change log, add reported-by tags]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230106065157.182648-1-kjain@linux.ibm.com
This commit is contained in:
Kajol Jain 2023-01-06 12:21:57 +05:30 committed by Michael Ellerman
parent 3287ebd7fd
commit 76d588dddc
2 changed files with 67 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/include/asm/imc-pmu.h
View File

@ -137,7 +137,7 @@ struct imc_pmu {
* are inited.
*/
struct imc_pmu_ref {
struct mutex lock;
spinlock_t lock;
unsigned int id;
int refc;
};

136
arch/powerpc/perf/imc-pmu.c
View File

@ -14,6 +14,7 @@
#include <asm/cputhreads.h>
#include <asm/smp.h>
#include <linux/string.h>
#include <linux/spinlock.h>
/* Nest IMC data structures and variables */
@ -21,7 +22,7 @@
* Used to avoid races in counting the nest-pmu units during hotplug
* register and unregister
*/
static DEFINE_MUTEX(nest_init_lock);
static DEFINE_SPINLOCK(nest_init_lock);
static DEFINE_PER_CPU(struct imc_pmu_ref *, local_nest_imc_refc);
static struct imc_pmu **per_nest_pmu_arr;
static cpumask_t nest_imc_cpumask;
@ -50,7 +51,7 @@ static int trace_imc_mem_size;
* core and trace-imc
*/
static struct imc_pmu_ref imc_global_refc = {
.lock = __MUTEX_INITIALIZER(imc_global_refc.lock),
.lock = __SPIN_LOCK_INITIALIZER(imc_global_refc.lock),
.id = 0,
.refc = 0,
};
@ -400,7 +401,7 @@ static int ppc_nest_imc_cpu_offline(unsigned int cpu)
get_hard_smp_processor_id(cpu));
/*
* If this is the last cpu in this chip then, skip the reference
* count mutex lock and make the reference count on this chip zero.
* count lock and make the reference count on this chip zero.
*/
ref = get_nest_pmu_ref(cpu);
if (!ref)
@ -462,15 +463,15 @@ static void nest_imc_counters_release(struct perf_event *event)
/*
* See if we need to disable the nest PMU.
* If no events are currently in use, then we have to take a
* mutex to ensure that we don't race with another task doing
* lock to ensure that we don't race with another task doing
* enable or disable the nest counters.
*/
ref = get_nest_pmu_ref(event->cpu);
if (!ref)
return;
/* Take the mutex lock for this node and then decrement the reference count */
mutex_lock(&ref->lock);
/* Take the lock for this node and then decrement the reference count */
spin_lock(&ref->lock);
if (ref->refc == 0) {
/*
* The scenario where this is true is, when perf session is
@ -482,7 +483,7 @@ static void nest_imc_counters_release(struct perf_event *event)
* an OPAL call to disable the engine in that node.
*
*/
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
return;
}
ref->refc--;
@ -490,7 +491,7 @@ static void nest_imc_counters_release(struct perf_event *event)
rc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_NEST,
get_hard_smp_processor_id(event->cpu));
if (rc) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("nest-imc: Unable to stop the counters for core %d\n", node_id);
return;
}
@ -498,7 +499,7 @@ static void nest_imc_counters_release(struct perf_event *event)
WARN(1, "nest-imc: Invalid event reference count\n");
ref->refc = 0;
}
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
}
static int nest_imc_event_init(struct perf_event *event)
@ -557,26 +558,25 @@ static int nest_imc_event_init(struct perf_event *event)
/*
* Get the imc_pmu_ref struct for this node.
* Take the mutex lock and then increment the count of nest pmu events
* inited.
* Take the lock and then increment the count of nest pmu events inited.
*/
ref = get_nest_pmu_ref(event->cpu);
if (!ref)
return -EINVAL;
mutex_lock(&ref->lock);
spin_lock(&ref->lock);
if (ref->refc == 0) {
rc = opal_imc_counters_start(OPAL_IMC_COUNTERS_NEST,
get_hard_smp_processor_id(event->cpu));
if (rc) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("nest-imc: Unable to start the counters for node %d\n",
node_id);
return rc;
}
}
++ref->refc;
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
event->destroy = nest_imc_counters_release;
return 0;
@ -612,9 +612,8 @@ static int core_imc_mem_init(int cpu, int size)
return -ENOMEM;
mem_info->vbase = page_address(page);
/* Init the mutex */
core_imc_refc[core_id].id = core_id;
mutex_init(&core_imc_refc[core_id].lock);
spin_lock_init(&core_imc_refc[core_id].lock);
rc = opal_imc_counters_init(OPAL_IMC_COUNTERS_CORE,
__pa((void *)mem_info->vbase),
@ -703,9 +702,8 @@ static int ppc_core_imc_cpu_offline(unsigned int cpu)
perf_pmu_migrate_context(&core_imc_pmu->pmu, cpu, ncpu);
} else {
/*
* If this is the last cpu in this core then, skip taking refernce
* count mutex lock for this core and directly zero "refc" for
* this core.
* If this is the last cpu in this core then skip taking reference
* count lock for this core and directly zero "refc" for this core.
*/
opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
get_hard_smp_processor_id(cpu));
@ -720,11 +718,11 @@ static int ppc_core_imc_cpu_offline(unsigned int cpu)
* last cpu in this core and core-imc event running
* in this cpu.
*/
mutex_lock(&imc_global_refc.lock);
spin_lock(&imc_global_refc.lock);
if (imc_global_refc.id == IMC_DOMAIN_CORE)
imc_global_refc.refc--;
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
}
return 0;
}
@ -739,7 +737,7 @@ static int core_imc_pmu_cpumask_init(void)
static void reset_global_refc(struct perf_event *event)
{
mutex_lock(&imc_global_refc.lock);
spin_lock(&imc_global_refc.lock);
imc_global_refc.refc--;
/*
@ -751,7 +749,7 @@ static void reset_global_refc(struct perf_event *event)
imc_global_refc.refc = 0;
imc_global_refc.id = 0;
}
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
}
static void core_imc_counters_release(struct perf_event *event)
@ -764,17 +762,17 @@ static void core_imc_counters_release(struct perf_event *event)
/*
* See if we need to disable the IMC PMU.
* If no events are currently in use, then we have to take a
* mutex to ensure that we don't race with another task doing
* lock to ensure that we don't race with another task doing
* enable or disable the core counters.
*/
core_id = event->cpu / threads_per_core;
/* Take the mutex lock and decrement the refernce count for this core */
/* Take the lock and decrement the refernce count for this core */
ref = &core_imc_refc[core_id];
if (!ref)
return;
mutex_lock(&ref->lock);
spin_lock(&ref->lock);
if (ref->refc == 0) {
/*
* The scenario where this is true is, when perf session is
@ -786,7 +784,7 @@ static void core_imc_counters_release(struct perf_event *event)
* an OPAL call to disable the engine in that core.
*
*/
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
return;
}
ref->refc--;
@ -794,7 +792,7 @@ static void core_imc_counters_release(struct perf_event *event)
rc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
get_hard_smp_processor_id(event->cpu));
if (rc) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("IMC: Unable to stop the counters for core %d\n", core_id);
return;
}
@ -802,7 +800,7 @@ static void core_imc_counters_release(struct perf_event *event)
WARN(1, "core-imc: Invalid event reference count\n");
ref->refc = 0;
}
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
reset_global_refc(event);
}
@ -840,7 +838,6 @@ static int core_imc_event_init(struct perf_event *event)
if ((!pcmi->vbase))
return -ENODEV;
/* Get the core_imc mutex for this core */
ref = &core_imc_refc[core_id];
if (!ref)
return -EINVAL;
@ -848,22 +845,22 @@ static int core_imc_event_init(struct perf_event *event)
/*
* Core pmu units are enabled only when it is used.
* See if this is triggered for the first time.
* If yes, take the mutex lock and enable the core counters.
* If yes, take the lock and enable the core counters.
* If not, just increment the count in core_imc_refc struct.
*/
mutex_lock(&ref->lock);
spin_lock(&ref->lock);
if (ref->refc == 0) {
rc = opal_imc_counters_start(OPAL_IMC_COUNTERS_CORE,
get_hard_smp_processor_id(event->cpu));
if (rc) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("core-imc: Unable to start the counters for core %d\n",
core_id);
return rc;
}
}
++ref->refc;
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
/*
* Since the system can run either in accumulation or trace-mode
@ -874,7 +871,7 @@ static int core_imc_event_init(struct perf_event *event)
* to know whether any other trace/thread imc
* events are running.
*/
mutex_lock(&imc_global_refc.lock);
spin_lock(&imc_global_refc.lock);
if (imc_global_refc.id == 0 || imc_global_refc.id == IMC_DOMAIN_CORE) {
/*
* No other trace/thread imc events are running in
@ -883,10 +880,10 @@ static int core_imc_event_init(struct perf_event *event)
imc_global_refc.id = IMC_DOMAIN_CORE;
imc_global_refc.refc++;
} else {
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
return -EBUSY;
}
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
event->hw.event_base = (u64)pcmi->vbase + (config & IMC_EVENT_OFFSET_MASK);
event->destroy = core_imc_counters_release;
@ -958,10 +955,10 @@ static int ppc_thread_imc_cpu_offline(unsigned int cpu)
mtspr(SPRN_LDBAR, (mfspr(SPRN_LDBAR) & (~(1UL << 63))));
/* Reduce the refc if thread-imc event running on this cpu */
mutex_lock(&imc_global_refc.lock);
spin_lock(&imc_global_refc.lock);
if (imc_global_refc.id == IMC_DOMAIN_THREAD)
imc_global_refc.refc--;
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
return 0;
}
@ -1001,7 +998,7 @@ static int thread_imc_event_init(struct perf_event *event)
if (!target)
return -EINVAL;
mutex_lock(&imc_global_refc.lock);
spin_lock(&imc_global_refc.lock);
/*
* Check if any other trace/core imc events are running in the
* system, if not set the global id to thread-imc.
@ -1010,10 +1007,10 @@ static int thread_imc_event_init(struct perf_event *event)
imc_global_refc.id = IMC_DOMAIN_THREAD;
imc_global_refc.refc++;
} else {
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
return -EBUSY;
}
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
event->pmu->task_ctx_nr = perf_sw_context;
event->destroy = reset_global_refc;
@ -1135,25 +1132,25 @@ static int thread_imc_event_add(struct perf_event *event, int flags)
/*
* imc pmus are enabled only when it is used.
* See if this is triggered for the first time.
* If yes, take the mutex lock and enable the counters.
* If yes, take the lock and enable the counters.
* If not, just increment the count in ref count struct.
*/
ref = &core_imc_refc[core_id];
if (!ref)
return -EINVAL;
mutex_lock(&ref->lock);
spin_lock(&ref->lock);
if (ref->refc == 0) {
if (opal_imc_counters_start(OPAL_IMC_COUNTERS_CORE,
get_hard_smp_processor_id(smp_processor_id()))) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("thread-imc: Unable to start the counter\
for core %d\n", core_id);
return -EINVAL;
}
}
++ref->refc;
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
return 0;
}
@ -1170,12 +1167,12 @@ static void thread_imc_event_del(struct perf_event *event, int flags)
return;
}
mutex_lock(&ref->lock);
spin_lock(&ref->lock);
ref->refc--;
if (ref->refc == 0) {
if (opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
get_hard_smp_processor_id(smp_processor_id()))) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("thread-imc: Unable to stop the counters\
for core %d\n", core_id);
return;
@ -1183,7 +1180,7 @@ static void thread_imc_event_del(struct perf_event *event, int flags)
} else if (ref->refc < 0) {
ref->refc = 0;
}
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
/* Set bit 0 of LDBAR to zero, to stop posting updates to memory */
mtspr(SPRN_LDBAR, (mfspr(SPRN_LDBAR) & (~(1UL << 63))));
@ -1224,9 +1221,8 @@ static int trace_imc_mem_alloc(int cpu_id, int size)
}
}
/* Init the mutex, if not already */
trace_imc_refc[core_id].id = core_id;
mutex_init(&trace_imc_refc[core_id].lock);
spin_lock_init(&trace_imc_refc[core_id].lock);
mtspr(SPRN_LDBAR, 0);
return 0;
@ -1246,10 +1242,10 @@ static int ppc_trace_imc_cpu_offline(unsigned int cpu)
* Reduce the refc if any trace-imc event running
* on this cpu.
*/
mutex_lock(&imc_global_refc.lock);
spin_lock(&imc_global_refc.lock);
if (imc_global_refc.id == IMC_DOMAIN_TRACE)
imc_global_refc.refc--;
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
return 0;
}
@ -1371,17 +1367,17 @@ static int trace_imc_event_add(struct perf_event *event, int flags)
}
mtspr(SPRN_LDBAR, ldbar_value);
mutex_lock(&ref->lock);
spin_lock(&ref->lock);
if (ref->refc == 0) {
if (opal_imc_counters_start(OPAL_IMC_COUNTERS_TRACE,
get_hard_smp_processor_id(smp_processor_id()))) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("trace-imc: Unable to start the counters for core %d\n", core_id);
return -EINVAL;
}
}
++ref->refc;
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
return 0;
}
@ -1414,19 +1410,19 @@ static void trace_imc_event_del(struct perf_event *event, int flags)
return;
}
mutex_lock(&ref->lock);
spin_lock(&ref->lock);
ref->refc--;
if (ref->refc == 0) {
if (opal_imc_counters_stop(OPAL_IMC_COUNTERS_TRACE,
get_hard_smp_processor_id(smp_processor_id()))) {
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
pr_err("trace-imc: Unable to stop the counters for core %d\n", core_id);
return;
}
} else if (ref->refc < 0) {
ref->refc = 0;
}
mutex_unlock(&ref->lock);
spin_unlock(&ref->lock);
trace_imc_event_stop(event, flags);
}
@ -1448,7 +1444,7 @@ static int trace_imc_event_init(struct perf_event *event)
* no other thread is running any core/thread imc
* events
*/
mutex_lock(&imc_global_refc.lock);
spin_lock(&imc_global_refc.lock);
if (imc_global_refc.id == 0 || imc_global_refc.id == IMC_DOMAIN_TRACE) {
/*
* No core/thread imc events are running in the
@ -1457,10 +1453,10 @@ static int trace_imc_event_init(struct perf_event *event)
imc_global_refc.id = IMC_DOMAIN_TRACE;
imc_global_refc.refc++;
} else {
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
return -EBUSY;
}
mutex_unlock(&imc_global_refc.lock);
spin_unlock(&imc_global_refc.lock);
event->hw.idx = -1;
@ -1533,10 +1529,10 @@ static int init_nest_pmu_ref(void)
i = 0;
for_each_node(nid) {
/*
* Mutex lock to avoid races while tracking the number of
* Take the lock to avoid races while tracking the number of
* sessions using the chip's nest pmu units.
*/
mutex_init(&nest_imc_refc[i].lock);
spin_lock_init(&nest_imc_refc[i].lock);
/*
* Loop to init the "id" with the node_id. Variable "i" initialized to
@ -1633,7 +1629,7 @@ static void imc_common_mem_free(struct imc_pmu *pmu_ptr)
static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
{
if (pmu_ptr->domain == IMC_DOMAIN_NEST) {
mutex_lock(&nest_init_lock);
spin_lock(&nest_init_lock);
if (nest_pmus == 1) {
cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE);
kfree(nest_imc_refc);
@ -1643,7 +1639,7 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
if (nest_pmus > 0)
nest_pmus--;
mutex_unlock(&nest_init_lock);
spin_unlock(&nest_init_lock);
}
/* Free core_imc memory */
@ -1800,11 +1796,11 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id
* rest. To handle the cpuhotplug callback unregister, we track
* the number of nest pmus in "nest_pmus".
*/
mutex_lock(&nest_init_lock);
spin_lock(&nest_init_lock);
if (nest_pmus == 0) {
ret = init_nest_pmu_ref();
if (ret) {
mutex_unlock(&nest_init_lock);
spin_unlock(&nest_init_lock);
kfree(per_nest_pmu_arr);
per_nest_pmu_arr = NULL;
goto err_free_mem;
@ -1812,7 +1808,7 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id
/* Register for cpu hotplug notification. */
ret = nest_pmu_cpumask_init();
if (ret) {
mutex_unlock(&nest_init_lock);
spin_unlock(&nest_init_lock);
kfree(nest_imc_refc);
kfree(per_nest_pmu_arr);
per_nest_pmu_arr = NULL;
@ -1820,7 +1816,7 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id
}
}
nest_pmus++;
mutex_unlock(&nest_init_lock);
spin_unlock(&nest_init_lock);
break;
case IMC_DOMAIN_CORE:
ret = core_imc_pmu_cpumask_init();