Commit fdf09ab8 authored Oct 08, 2020 by Daniel Jordan Committed by Jessica Yu Oct 12, 2020

module: statically initialize init section freeing data

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 c4741b23 ("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: 1a7b7d92 ("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>

parent 14721add

kernel/module.c

+3 −10

Original line number	Diff line number	Diff line
		@@ -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

		@@ -3582,14 +3583,6 @@ 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.
		*

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