Re: [Patch] hugetlb: remove user_shm_lock() check fromhugetlb_file_setup()

From: David Rientjes
Date: Sat Jun 18 2011 - 19:38:31 EST

On Sat, 18 Jun 2011, AmÃrico Wang wrote:

> This is a revert of
> commit 2584e517320bd48dc8d20e38a2621a2dbe58fade
> Author: Ravikiran G Thirumalai <kiran@xxxxxxxxxxxx>
> Date: Tue Mar 31 15:21:26 2009 -0700
> mm: reintroduce and deprecate rlimit based access for SHM_HUGETLB
> because it is deprecated and scheduled to be removed.

I know this is scheduled for removal and it is quite past due, but I think
we need to do some due diligence before just yanking the whole thing out.
A printk_once() about some mysterious application using SHM_HUGETLB
doesn't seem very helpful in migrating users to start using
/proc/sys/vm/hugetlb_shm_group, and suddenly returning -EPERM when
attempting it doesn't seem very responsible, despite what
Documentation/feature-removal-schedule.txt may say.

For context, we just ran into this internally where this warning at one
point appeared to be WARN_ON_ONCE(). That seems more attention grabbing
because it at least allows users to start understanding what the issue is
and who needs to be fixed.