3.16.84-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Daniel Jordan <daniel.m.jor...@oracle.com>
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 <daniel.m.jor...@oracle.com>
Cc: Eric Biggers <ebigg...@kernel.org>
Cc: Herbert Xu <herb...@gondor.apana.org.au>
Cc: Steffen Klassert <steffen.klass...@secunet.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Herbert Xu <herb...@gondor.apana.org.au>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
kernel/padata.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -614,8 +614,8 @@ int padata_set_cpumask(struct padata_ins
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:
@@ -633,8 +633,8 @@ int padata_set_cpumask(struct padata_ins
err = __padata_set_cpumasks(pinst, parallel_mask, serial_mask);
out:
- put_online_cpus();
mutex_unlock(&pinst->lock);
+ put_online_cpus();
return err;
}
