The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

76d588dddc45 ("powerpc/imc-pmu: Fix use of mutex in IRQs disabled section") a36e8ba60b99 ("powerpc/perf: Implement a global lock to avoid races between trace, core and thread imc events.") 012ae244845f ("powerpc/perf: Trace imc PMU functions") 72c69dcddce1 ("powerpc/perf: Trace imc events detection and cpuhotplug") dd50cf7cbc7b ("powerpc/perf: Rearrange setting of ldbar for thread-imc") 4851f75098bc ("powerpc/perf: Declare static identifier a such")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 76d588dddc459fefa1da96e0a081a397c5c8e216 Mon Sep 17 00:00:00 2001 From: Kajol Jain kjain@linux.ibm.com Date: Fri, 6 Jan 2023 12:21:57 +0530 Subject: [PATCH] powerpc/imc-pmu: Fix use of mutex in IRQs disabled section

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: 8f95faaac56c ("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

diff --git a/arch/powerpc/include/asm/imc-pmu.h b/arch/powerpc/include/asm/imc-pmu.h index 4f897993b710..699a88584ae1 100644 --- a/arch/powerpc/include/asm/imc-pmu.h +++ b/arch/powerpc/include/asm/imc-pmu.h @@ -137,7 +137,7 @@ struct imc_pmu { * are inited. */ struct imc_pmu_ref { - struct mutex lock; + spinlock_t lock; unsigned int id; int refc; }; diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c index d517aba94d1b..100e97daf76b 100644 --- a/arch/powerpc/perf/imc-pmu.c +++ b/arch/powerpc/perf/imc-pmu.c @@ -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();