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| author | Daniel Jordan <daniel.m.jordan@oracle.com> | 2019-12-03 14:31:11 -0500 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2020-05-22 21:19:15 +0100 |
| commit | 1c115b879a9cf24999a0d896bc5d9af9049a6258 (patch) | |
| tree | 214bb260336c7022d52c26cd08a0dfb1e1fea6f1 | |
| parent | 8321a1cf93ac54958ad6348aa833d3cf17ff77a2 (diff) | |
| download | linux-stable-1c115b879a9cf24999a0d896bc5d9af9049a6258.tar.gz | |
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 <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>
| -rw-r--r-- | kernel/padata.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/padata.c b/kernel/padata.c index 281d752151c47..3dbd6d4702183 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -620,8 +620,8 @@ 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: @@ -639,8 +639,8 @@ 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; } |