Re: [Patch] hugetlb: remove user_shm_lock() check from hugetlb_file_setup()

["Américo Wang" <xiyou.wangcong@gmail.com>]

On Sun, Jun 19, 2011 at 7:34 AM, David Rientjes <rientjes@google.com> wrote:
> On Sat, 18 Jun 2011, Américo Wang wrote:
>
>>
>> This is a revert of
>>
>> commit 2584e517320bd48dc8d20e38a2621a2dbe58fade
>> Author: Ravikiran G Thirumalai <kiran@scalex86.org>
>> 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.

Well, we put printk_once with KERN_WARNING level, this is already an enough
warning, the only difference with WARN_ON_ONCE() is this has no backtrace
which is not important for this case.

Thanks.