4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Lu Jialin lujialin4@huawei.com
[ Upstream commit 8f4f68e788c3a7a696546291258bfa5fdb215523 ]
We found a hungtask bug in test_aead_vec_cfg as follows:
INFO: task cryptomgr_test:391009 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Call trace: __switch_to+0x98/0xe0 __schedule+0x6c4/0xf40 schedule+0xd8/0x1b4 schedule_timeout+0x474/0x560 wait_for_common+0x368/0x4e0 wait_for_completion+0x20/0x30 wait_for_completion+0x20/0x30 test_aead_vec_cfg+0xab4/0xd50 test_aead+0x144/0x1f0 alg_test_aead+0xd8/0x1e0 alg_test+0x634/0x890 cryptomgr_test+0x40/0x70 kthread+0x1e0/0x220 ret_from_fork+0x10/0x18 Kernel panic - not syncing: hung_task: blocked tasks
For padata_do_parallel, when the return err is 0 or -EBUSY, it will call wait_for_completion(&wait->completion) in test_aead_vec_cfg. In normal case, aead_request_complete() will be called in pcrypt_aead_serial and the return err is 0 for padata_do_parallel. But, when pinst->flags is PADATA_RESET, the return err is -EBUSY for padata_do_parallel, and it won't call aead_request_complete(). Therefore, test_aead_vec_cfg will hung at wait_for_completion(&wait->completion), which will cause hungtask.
The problem comes as following: (padata_do_parallel) | rcu_read_lock_bh(); | err = -EINVAL; | (padata_replace) | pinst->flags |= PADATA_RESET; err = -EBUSY | if (pinst->flags & PADATA_RESET) | rcu_read_unlock_bh() | return err
In order to resolve the problem, we replace the return err -EBUSY with -EAGAIN, which means parallel_data is changing, and the caller should call it again.
v3: remove retry and just change the return err. v2: introduce padata_try_do_parallel() in pcrypt_aead_encrypt and pcrypt_aead_decrypt to solve the hungtask.
Signed-off-by: Lu Jialin lujialin4@huawei.com Signed-off-by: Guo Zihua guozihua@huawei.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Sasha Levin sashal@kernel.org --- crypto/pcrypt.c | 4 ++++ kernel/padata.c | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/crypto/pcrypt.c b/crypto/pcrypt.c index 62e11835f220e..1e9de81ef84fa 100644 --- a/crypto/pcrypt.c +++ b/crypto/pcrypt.c @@ -174,6 +174,8 @@ static int pcrypt_aead_encrypt(struct aead_request *req) err = pcrypt_do_parallel(padata, &ctx->cb_cpu, &pencrypt); if (!err) return -EINPROGRESS; + if (err == -EBUSY) + return -EAGAIN;
return err; } @@ -218,6 +220,8 @@ static int pcrypt_aead_decrypt(struct aead_request *req) err = pcrypt_do_parallel(padata, &ctx->cb_cpu, &pdecrypt); if (!err) return -EINPROGRESS; + if (err == -EBUSY) + return -EAGAIN;
return err; } diff --git a/kernel/padata.c b/kernel/padata.c index f56ec63f60ba8..82f6d5bf5cb45 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -120,7 +120,7 @@ int padata_do_parallel(struct padata_instance *pinst, if (!cpumask_test_cpu(cb_cpu, pd->cpumask.cbcpu)) goto out;
- err = -EBUSY; + err = -EBUSY; if ((pinst->flags & PADATA_RESET)) goto out;