Re: [PATCH v2] Fix regression due to "fs: move binfmt_misc sysctl to its own file"

[Ido Schimmel]

On Wed, Feb 09, 2022 at 08:49:20AM +0100, Domenico Andreoli wrote:
>  fs/binfmt_misc.c |    6 +-----
>  fs/file_table.c  |    2 ++
>  2 files changed, 3 insertions(+), 5 deletions(-)
> 
> Index: b/fs/binfmt_misc.c
> ===================================================================
> --- a/fs/binfmt_misc.c
> +++ b/fs/binfmt_misc.c
> @@ -817,20 +817,16 @@ static struct file_system_type bm_fs_typ
>  };
>  MODULE_ALIAS_FS("binfmt_misc");
>  
> -static struct ctl_table_header *binfmt_misc_header;
> -
>  static int __init init_misc_binfmt(void)
>  {
>  	int err = register_filesystem(&bm_fs_type);
>  	if (!err)
>  		insert_binfmt(&misc_format);
> -	binfmt_misc_header = register_sysctl_mount_point("fs/binfmt_misc");
> -	return 0;
> +	return err;
>  }
>  
>  static void __exit exit_misc_binfmt(void)
>  {
> -	unregister_sysctl_table(binfmt_misc_header);
>  	unregister_binfmt(&misc_format);
>  	unregister_filesystem(&bm_fs_type);
>  }
> Index: b/fs/file_table.c
> ===================================================================
> --- a/fs/file_table.c
> +++ b/fs/file_table.c
> @@ -119,6 +119,8 @@ static struct ctl_table fs_stat_sysctls[
>  static int __init init_fs_stat_sysctls(void)
>  {
>  	register_sysctl_init("fs", fs_stat_sysctls);
> +	if (IS_ENABLED(CONFIG_BINFMT_MISC))
> +		register_sysctl_mount_point("fs/binfmt_misc");

Hi,

kmemleak complains about this:

# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8881045fea88 (size 96):
  comm "swapper/0", pid 1, jiffies 4294669355 (age 167.804s)
  hex dump (first 32 bytes):
    e0 c8 07 88 ff ff ff ff 00 00 00 00 01 00 00 00  ................
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff81d11637>] __register_sysctl_table+0x117/0x1150
    [<ffffffff86c3600f>] init_fs_stat_sysctls+0x30/0x33
    [<ffffffff81002558>] do_one_initcall+0x108/0x690
    [<ffffffff86bca8bd>] kernel_init_freeable+0x45a/0x4de
    [<ffffffff83e0757f>] kernel_init+0x1f/0x220
    [<ffffffff810048cf>] ret_from_fork+0x1f/0x30

>  	return 0;
>  }
>  fs_initcall(init_fs_stat_sysctls);
>