3.16.84-rc1 review patch. If anyone has any objections, please let me know.
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From: Daniel Jordan daniel.m.jordan@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.jordan@oracle.com Cc: Eric Biggers ebiggers@kernel.org Cc: Herbert Xu herbert@gondor.apana.org.au Cc: Steffen Klassert steffen.klassert@secunet.com Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Ben Hutchings ben@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; }