| Message ID | 20230809125048.503619-1-lujialin4@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | crypto:padata: Fix return err for PADATA_RESET | expand |
Lu Jialin <lujialin4@huawei.com> wrote: > 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 > 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, change the return err to -EINVAL when > pinst->flags is set PADATA_RESET. > > Signed-off-by: Lu Jialin <lujialin4@huawei.com> > --- > kernel/padata.c | 1 - > 1 file changed, 1 deletion(-) Thanks for the patch. So the issue here is that the Crypto API uses EBUSY for a specific purpose but padata uses it too and they're getting confused with each other. I think what we should do is get pcrypt to check the error value from padata_do_parallel, and if it's EBUSY then change it to something else. Thanks,
diff --git a/kernel/padata.c b/kernel/padata.c index 222d60195de6..cc326ffb209a 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -202,7 +202,6 @@ int padata_do_parallel(struct padata_shell *ps, *cb_cpu = cpu; } - err = -EBUSY; if ((pinst->flags & PADATA_RESET)) goto out;
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 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, change the return err to -EINVAL when pinst->flags is set PADATA_RESET. Signed-off-by: Lu Jialin <lujialin4@huawei.com> --- kernel/padata.c | 1 - 1 file changed, 1 deletion(-)