lockdep complains when...
# echo 0 > /sys/devices/system/cpu/cpu1/online
# echo ff > /sys/kernel/pcrypt/pencrypt/parallel_cpumask
======================================================
WARNING: possible circular locking dependency detected
5.3.0-rc5-padata-base+ #6 Not tainted
------------------------------------------------------
bash/258 is trying to acquire lock:
00000000c43f7f29 (cpu_hotplug_lock.rw_sem){++++}, at: padata_set_cpumask+0x30/0x130
but task is already holding lock:
00000000676aa31d (&pinst->lock){+.+.}, at: padata_set_cpumask+0x2b/0x130
which lock already depends on the new lock.
padata doesn't take cpu_hotplug_lock and pinst->lock in a consistent
order. Which should be first? CPU hotplug calls into padata with
cpu_hotplug_lock already held, so it should have priority.
Fixes: 6751fb3c0e0c ("padata: Use get_online_cpus/put_online_cpus")
Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-crypto@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
kernel/padata.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/padata.c b/kernel/padata.c
index 6adce3b203fe..75e668fedd8d 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -603,8 +603,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
struct cpumask *serial_mask, *parallel_mask;
int err = -EINVAL;
- mutex_lock(&pinst->lock);
get_online_cpus();
+ mutex_lock(&pinst->lock);
switch (cpumask_type) {
case PADATA_CPU_PARALLEL:
@@ -622,8 +622,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
err = __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
out:
- put_online_cpus();
mutex_unlock(&pinst->lock);
+ put_online_cpus();
return err;
}
--
2.23.0
