This is a note to let you know that I've just added the patch titled
powerpc/imc-pmu: Revert nest_init_lock to being a mutex
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-imc-pmu-revert-nest_init_lock-to-being-a-mutex.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ad53db4acb415976761d7302f5b02e97f2bd097e Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Date: Mon, 30 Jan 2023 12:44:01 +1100
Subject: powerpc/imc-pmu: Revert nest_init_lock to being a mutex
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
commit ad53db4acb415976761d7302f5b02e97f2bd097e upstream.
The recent commit 76d588dddc45 ("powerpc/imc-pmu: Fix use of mutex in
IRQs disabled section") fixed warnings (and possible deadlocks) in the
IMC PMU driver by converting the locking to use spinlocks.
It also converted the init-time nest_init_lock to a spinlock, even
though it's not used at runtime in IRQ disabled sections or while
holding other spinlocks.
This leads to warnings such as:
BUG: sleeping function called from invalid context at include/linux/percpu-rwsem.h:49
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0
preempt_count: 1, expected: 0
CPU: 7 PID: 1 Comm: swapper/0 Not tainted 6.2.0-rc2-14719-gf12cd06109f4-dirty #1
Hardware name: Mambo,Simulated-System POWER9 0x4e1203 opal:v6.6.6 PowerNV
Call Trace:
dump_stack_lvl+0x74/0xa8 (unreliable)
__might_resched+0x178/0x1a0
__cpuhp_setup_state+0x64/0x1e0
init_imc_pmu+0xe48/0x1250
opal_imc_counters_probe+0x30c/0x6a0
platform_probe+0x78/0x110
really_probe+0x104/0x420
__driver_probe_device+0xb0/0x170
driver_probe_device+0x58/0x180
__driver_attach+0xd8/0x250
bus_for_each_dev+0xb4/0x140
driver_attach+0x34/0x50
bus_add_driver+0x1e8/0x2d0
driver_register+0xb4/0x1c0
__platform_driver_register+0x38/0x50
opal_imc_driver_init+0x2c/0x40
do_one_initcall+0x80/0x360
kernel_init_freeable+0x310/0x3b8
kernel_init+0x30/0x1a0
ret_from_kernel_thread+0x5c/0x64
Fix it by converting nest_init_lock back to a mutex, so that we can call
sleeping functions while holding it. There is no interaction between
nest_init_lock and the runtime spinlocks used by the actual PMU routines.
Fixes: 76d588dddc45 ("powerpc/imc-pmu: Fix use of mutex in IRQs disabled section")
Tested-by: Kajol Jain<kjain@xxxxxxxxxxxxx>
Reviewed-by: Kajol Jain<kjain@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230130014401.540543-1-mpe@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/perf/imc-pmu.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -21,7 +21,7 @@
* Used to avoid races in counting the nest-pmu units during hotplug
* register and unregister
*/
-static DEFINE_SPINLOCK(nest_init_lock);
+static DEFINE_MUTEX(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;
@@ -1621,7 +1621,7 @@ static void imc_common_mem_free(struct i
static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
{
if (pmu_ptr->domain == IMC_DOMAIN_NEST) {
- spin_lock(&nest_init_lock);
+ mutex_lock(&nest_init_lock);
if (nest_pmus == 1) {
cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE);
kfree(nest_imc_refc);
@@ -1631,7 +1631,7 @@ static void imc_common_cpuhp_mem_free(st
if (nest_pmus > 0)
nest_pmus--;
- spin_unlock(&nest_init_lock);
+ mutex_unlock(&nest_init_lock);
}
/* Free core_imc memory */
@@ -1788,11 +1788,11 @@ int init_imc_pmu(struct device_node *par
* rest. To handle the cpuhotplug callback unregister, we track
* the number of nest pmus in "nest_pmus".
*/
- spin_lock(&nest_init_lock);
+ mutex_lock(&nest_init_lock);
if (nest_pmus == 0) {
ret = init_nest_pmu_ref();
if (ret) {
- spin_unlock(&nest_init_lock);
+ mutex_unlock(&nest_init_lock);
kfree(per_nest_pmu_arr);
per_nest_pmu_arr = NULL;
goto err_free_mem;
@@ -1800,7 +1800,7 @@ int init_imc_pmu(struct device_node *par
/* Register for cpu hotplug notification. */
ret = nest_pmu_cpumask_init();
if (ret) {
- spin_unlock(&nest_init_lock);
+ mutex_unlock(&nest_init_lock);
kfree(nest_imc_refc);
kfree(per_nest_pmu_arr);
per_nest_pmu_arr = NULL;
@@ -1808,7 +1808,7 @@ int init_imc_pmu(struct device_node *par
}
}
nest_pmus++;
- spin_unlock(&nest_init_lock);
+ mutex_unlock(&nest_init_lock);
break;
case IMC_DOMAIN_CORE:
ret = core_imc_pmu_cpumask_init();
Patches currently in stable-queue which might be from mpe@xxxxxxxxxxxxxx are
queue-5.10/powerpc-bpf-change-register-numbering-for-bpf_set-is.patch
queue-5.10/powerpc-imc-pmu-revert-nest_init_lock-to-being-a-mutex.patch
queue-5.10/powerpc-bpf-move-common-helpers-into-bpf_jit.h.patch
