[PATCH AUTOSEL 6.5 04/34] crypto: pcrypt - Fix hungtask for PADATA_RESET

Sasha Levin
2023-11-07T15:51:46Z

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 8c1d0ca412137..d0d954fe9d54f 100644
--- a/crypto/pcrypt.c
+++ b/crypto/pcrypt.c
@@ -117,6 +117,8 @@ static int pcrypt_aead_encrypt(struct aead_request *req)
err = padata_do_parallel(ictx->psenc, padata, &ctx->cb_cpu);
if (!err)
return -EINPROGRESS;
+ if (err == -EBUSY)
+ return -EAGAIN;

return err;
}
@@ -164,6 +166,8 @@ static int pcrypt_aead_decrypt(struct aead_request *req)
err = padata_do_parallel(ictx->psdec, padata, &ctx->cb_cpu);
if (!err)
return -EINPROGRESS;
+ if (err == -EBUSY)
+ return -EAGAIN;

return err;
}
diff --git a/kernel/padata.c b/kernel/padata.c
index 222d60195de66..81c8183f3176a 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -202,7 +202,7 @@ int padata_do_parallel(struct padata_shell *ps,
*cb_cpu = cpu;
}

- err = -EBUSY;
+ err = -EBUSY;
if ((pinst->flags & PADATA_RESET))
goto out;

--
2.42.0