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

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Message-Id: <20190430221807.2418-1-prarit@redhat.com>
Date:   Tue, 30 Apr 2019 18:18:07 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Prarit Bhargava <prarit@...hat.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Jessica Yu <jeyu@...nel.org>
Subject: [PATCH v2] kernel/module: Reschedule while waiting for modules to finish loading

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@...ibm.com>
Fixes: commit f9a75c1d717f ("modules: Only return -EEXIST for modules that have finished loading")
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Jessica Yu <jeyu@...nel.org>
Cc: Heiko Carstens <heiko.carstens@...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