Re: [PATCHv3] locks: Filter /proc/locks output on proc pid ns

From: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>
To: Nikolay Borisov <kernel-6AxghH7DbtA@public.gmane.org>,
	bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	xemul-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org,
	avagin-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org,
	ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org
Subject: Re: [PATCHv3] locks: Filter /proc/locks output on proc pid ns
Date: Wed, 03 Aug 2016 11:24:50 -0400	[thread overview]
Message-ID: <1470237890.13804.2.camel@poochiereds.net> (raw)
In-Reply-To: <1470236078-2389-1-git-send-email-kernel-6AxghH7DbtA@public.gmane.org>

On Wed, 2016-08-03 at 17:54 +0300, Nikolay Borisov wrote:
> On busy container servers reading /proc/locks shows all the locks
> created by all clients. This can cause large latency spikes. In my
> case I observed lsof taking up to 5-10 seconds while processing around
> 50k locks. Fix this by limiting the locks shown only to those created
> in the same pidns as the one the proc fs was mounted in. When reading
> /proc/locks from the init_pid_ns proc instance then perform no
> filtering
> 
> > Signed-off-by: Nikolay Borisov <kernel@kyup.com>
> ---
>  fs/locks.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/locks.c b/fs/locks.c
> index ee1b15f6fc13..65e75810a836 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -2648,9 +2648,14 @@ static int locks_show(struct seq_file *f, void *v)
>  {
> >  	struct locks_iterator *iter = f->private;
> >  	struct file_lock *fl, *bfl;
> > +	struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;
>  
> >  	fl = hlist_entry(v, struct file_lock, fl_link);
>  
> > +	if ((proc_pidns != &init_pid_ns) && fl->fl_nspid
> > +	    && (proc_pidns != ns_of_pid(fl->fl_nspid)))
> > +		return 0;
> +
> >  	lock_get_status(f, fl, iter->li_pos, "");
>  
> >  	list_for_each_entry(bfl, &fl->fl_block, fl_block)

Yeah, that makes much more sense to me. I'll plan to merge this for
v4.9 unless there are objections between now and the next merge window.

Thanks,
-- 
Jeff Layton <jlayton@poochiereds.net>
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