[PATCH v2] kernel/module: Reschedule while waiting for modules to finish loading

[PATCH v2] kernel/module: Reschedule while waiting for modules to finish loading

[Prarit Bhargava]

On a s390 z14 LAR with 2 cpus about stalls about 3% of the time while
loading the s390_trng.ko module.

Add a reschedule point to the loop that waits for modules to complete
loading.

v2: cleanup Fixes line.

Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Fixes: commit f9a75c1d717f ("modules: Only return -EEXIST for modules that have finished loading")
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
---
 kernel/module.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/module.c b/kernel/module.c
index 410eeb7e4f1d..48748cfec991 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3585,6 +3585,7 @@ static int add_unformed_module(struct module *mod)
 					       finished_loading(mod->name));
 			if (err)
 				goto out_unlocked;
+			cond_resched();
 			goto again;
 		}
 		err = -EEXIST;
-- 
2.18.1

Re: [PATCH v2] kernel/module: Reschedule while waiting for modules to finish loading

[Prarit Bhargava]

On 4/30/19 6:18 PM, Prarit Bhargava wrote:
> On a s390 z14 LAR with 2 cpus about stalls about 3% of the time while
> loading the s390_trng.ko module.
> 
> Add a reschedule point to the loop that waits for modules to complete
> loading.
> 

Sorry, sent in error.

P.

> v2: cleanup Fixes line.
> 
> Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> Fixes: commit f9a75c1d717f ("modules: Only return -EEXIST for modules that have finished loading")
> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
> Cc: Jessica Yu <jeyu@kernel.org>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> ---
>  kernel/module.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/module.c b/kernel/module.c
> index 410eeb7e4f1d..48748cfec991 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3585,6 +3585,7 @@ static int add_unformed_module(struct module *mod)
>  					       finished_loading(mod->name));
>  			if (err)
>  				goto out_unlocked;
> +			cond_resched();
>  			goto again;
>  		}
>  		err = -EEXIST;
>