[PATCH 5.9 541/757] module: statically initialize init section freeing data

Greg Kroah-Hartman
2020-10-27T16:40:49Z

From: Daniel Jordan <daniel.m.jordan@oracle.com>

[ Upstream commit fdf09ab887829cd1b671e45d9549f8ec1ffda0fa ]

Corentin hit the following workqueue warning when running with
CRYPTO_MANAGER_EXTRA_TESTS:

WARNING: CPU: 2 PID: 147 at kernel/workqueue.c:1473 __queue_work+0x3b8/0x3d0
Modules linked in: ghash_generic
CPU: 2 PID: 147 Comm: modprobe Not tainted
5.6.0-rc1-next-20200214-00068-g166c9264f0b1-dirty #545
Hardware name: Pine H64 model A (DT)
pc : __queue_work+0x3b8/0x3d0
Call trace:
__queue_work+0x3b8/0x3d0
queue_work_on+0x6c/0x90
do_init_module+0x188/0x1f0
load_module+0x1d00/0x22b0

I wasn't able to reproduce on x86 or rpi 3b+.

This is

WARN_ON(!list_empty(&work->entry))

from __queue_work(), and it happens because the init_free_wq work item
isn't initialized in time for a crypto test that requests the gcm
module. Some crypto tests were recently moved earlier in boot as
explained in commit c4741b230597 ("crypto: run initcalls for generic
implementations earlier"), which went into mainline less than two weeks
before the Fixes commit.

Avoid the warning by statically initializing init_free_wq and the
corresponding llist.

Link: https://lore.kernel.org/lkml/20200217204803.GA13479@Red/
Fixes: 1a7b7d922081 ("modules: Use vmalloc special flag")
Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-on: sun50i-h6-pine-h64
Tested-on: imx8mn-ddr4-evk
Tested-on: sun50i-a64-bananapi-m64
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/module.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 1c5cff34d9f28..8486123ffd7af 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -91,8 +91,9 @@ EXPORT_SYMBOL_GPL(module_mutex);
static LIST_HEAD(modules);

/* Work queue for freeing init sections in success case */
-static struct work_struct init_free_wq;
-static struct llist_head init_free_list;
+static void do_free_init(struct work_struct *w);
+static DECLARE_WORK(init_free_wq, do_free_init);
+static LLIST_HEAD(init_free_list);

#ifdef CONFIG_MODULES_TREE_LOOKUP

@@ -3579,14 +3580,6 @@ static void do_free_init(struct work_struct *w)
}
}

-static int __init modules_wq_init(void)
-{
- INIT_WORK(&init_free_wq, do_free_init);
- init_llist_head(&init_free_list);
- return 0;
-}
-module_init(modules_wq_init);
-
/*
* This is where the real work happens.
*
--
2.25.1