Re: [PATCH RESEND v2] mm,hugetlb: remove mlock ulimit for SHM_HUGETLB

[Michal Hocko <mhocko@suse.com>]

On Fri 08-10-21 14:26:48, Mike Kravetz wrote:
> On 10/8/21 12:57 PM, zhangyiru wrote:
> > commit 21a3c273f88c9cbbaf7e ("mm, hugetlb: add thread name and pid to
> > SHM_HUGETLB mlock rlimit warning") marked this as deprecated in 2012,
> > but it is not deleted yet.
> > 
> > Mike says he still see that message in log files on occasion,
> > so maybe we should preserve this warning.
> > 
> > Signed-off-by: zhangyiru <zhangyiru3@huawei.com>
> > ---
> > Changelog:
> >  v2: preserve warning message
> >  v1: remove mlock ulimit for SHM_HUGETLB
> > ---
> >  fs/hugetlbfs/inode.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> > index cdfb1ae78a3f..877d0ce9526c 100644
> > --- a/fs/hugetlbfs/inode.c
> > +++ b/fs/hugetlbfs/inode.c
> > @@ -1470,10 +1470,9 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
> >  			pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is deprecated\n",
> >  				current->comm, current->pid);
> >  			task_unlock(current);
> > -		} else {
> > -			*ucounts = NULL;
> > -			return ERR_PTR(-EPERM);
> >  		}
> > +		*ucounts = NULL;
> > +		return ERR_PTR(-EPERM);
> 
> IIUC, deprecated means that use of the feature is discouraged but
> technically still available.  With this patch, we use the term
> deprecated and also remove the functionality.  Perhaps change the
> warning to be the following?
> 
> pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is now obsolete\n",

Agreed. I would even go with an addition "Please report if you have a
usecase for this functionality."

> Leaving the 'deprecated' message and removing the functionality may
> confuse people if their application breaks after this patch.
> -- 
> Mike Kravetz

-- 
Michal Hocko
SUSE Labs