blob: e059b3cec8311b9f3f9059f1d0c2aa640afaf2ee [file] [log] [blame]
From ccfe2fb1ed3e11b80eba9f2b0330fcecad08f295 Mon Sep 17 00:00:00 2001
From: Daniel Jordan <>
Date: Tue, 3 Dec 2019 14:31:11 -0500
Subject: [PATCH] padata: always acquire cpu_hotplug_lock before pinst->lock
commit 38228e8848cd7dd86ccb90406af32de0cad24be3 upstream.
lockdep complains when padata's paths to update cpumasks via CPU hotplug
and sysfs are both taken:
# echo 0 > /sys/devices/system/cpu/cpu1/online
# echo ff > /sys/kernel/pcrypt/pencrypt/parallel_cpumask
WARNING: possible circular locking dependency detected
5.4.0-rc8-padata-cpuhp-v3+ #1 Not tainted
bash/205 is trying to acquire lock:
ffffffff8286bcd0 (cpu_hotplug_lock.rw_sem){++++}, at: padata_set_cpumask+0x2b/0x120
but task is already holding lock:
ffff8880001abfa0 (&pinst->lock){+.+.}, at: padata_set_cpumask+0x26/0x120
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 <>
Cc: Eric Biggers <>
Cc: Herbert Xu <>
Cc: Steffen Klassert <>
Signed-off-by: Herbert Xu <>
Signed-off-by: Paul Gortmaker <>
diff --git a/kernel/padata.c b/kernel/padata.c
index 161bda8370a6..4f39a5e7a853 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -671,8 +671,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
struct cpumask *serial_mask, *parallel_mask;
int err = -EINVAL;
- mutex_lock(&pinst->lock);
+ mutex_lock(&pinst->lock);
switch (cpumask_type) {
@@ -690,8 +690,8 @@ int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,
err = __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
- put_online_cpus();
+ put_online_cpus();
return err;