Question about admin_reserve_kbytes in GUESS mode

[Chunyu Hu <chuhu@xxxxxxxxxx>]

Hello experts,

I find admin_reserve_kbytes is not working as documented since

commit 8c7829b04c523cdc(mm: fix false-positive OVERCOMMIT_GUESS failures).

Before that, available free pages are used to determine the allocation check,  and admin_reserve_kbytes

was honored in the default GUESS over_commit mode. While after that commit, admin_reserve_kbytes

is not honored in default mode any more. This looks like break the sysctl usage?

Documentation/admin-guide/sysctl/vm.rst:

admin_reserve_kbytes
====================

The amount of free memory in the system that should be reserved for users
with the capability cap_sys_admin.
                                                                                                                                                                             
admin_reserve_kbytes defaults to min(3% of free pages, 8MB)

That should provide enough for the admin to log in and kill a process,
if necessary, under the default overcommit 'guess' mode.

.......

--

Regards,
Chunyu Hu