> On Feb 13, 2022, at 7:34 AM, Ido Schimmel <idosch@idosch.org> wrote:
> 
> 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);

Hi Ido,
Thanks for the report. This is a known issue. The fix is proposed here.
https://lore.kernel.org/all/YgRbEG21AUrLSFKX@bombadil.infradead.org/ <https://lore.kernel.org/all/YgRbEG21AUrLSFKX@bombadil.infradead.org/>

Thanks,
- Tong