Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 23 May 2019 22:07:17 +0900
From:   Minchan Kim <minchan@kernel.org>
To:     Daniel Colascione <dancol@google.com>
Cc:     Christian Brauner <christian@brauner.io>,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>, Michal Hocko <mhocko@suse.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Tim Murray <timmurray@google.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Shakeel Butt <shakeelb@google.com>,
        Sonny Rao <sonnyrao@google.com>,
        Brian Geffon <bgeffon@google.com>, Jann Horn <jannh@google.com>
Subject: Re: [RFC 0/7] introduce memory hinting API for external process
Message-ID: <20190523130717.GA203306@google.com>
References: <20190521113911.2rypoh7uniuri2bj@brauner.io>
 <CAKOZuesjDcD3EM4PS7aO7yTa3KZ=FEzMP63MR0aEph4iW1NCYQ@mail.gmail.com>
 <CAHrFyr6iuoZ-r6e57zp1rz7b=Ee0Vko+syuUKW2an+TkAEz_iA@mail.gmail.com>
 <CAKOZueupb10vmm-bmL0j_b__qsC9ZrzhzHgpGhwPVUrfX0X-Og@mail.gmail.com>
 <20190522145216.jkimuudoxi6pder2@brauner.io>
 <CAKOZueu837QGDAGat-tdA9J1qtKaeuQ5rg0tDyEjyvd_hjVc6g@mail.gmail.com>
 <20190522154823.hu77qbjho5weado5@brauner.io>
 <CAKOZuev97fTvmXhEkjb7_RfDvjki4UoPw+QnVOsSAg0RB8RyMQ@mail.gmail.com>
 <20190522160108.l5i7t4lkfy3tyx3z@brauner.io>
 <CAKOZuevR2WTbeFdvpx8K9jJj0Sc=wpNJKr24ePWsvE_WS5wgNw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAKOZuevR2WTbeFdvpx8K9jJj0Sc=wpNJKr24ePWsvE_WS5wgNw@mail.gmail.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, May 22, 2019 at 09:01:33AM -0700, Daniel Colascione wrote:
> On Wed, May 22, 2019 at 9:01 AM Christian Brauner <christian@brauner.io> wrote:
> >
> > On Wed, May 22, 2019 at 08:57:47AM -0700, Daniel Colascione wrote:
> > > On Wed, May 22, 2019 at 8:48 AM Christian Brauner <christian@brauner.io> wrote:
> > > >
> > > > On Wed, May 22, 2019 at 08:17:23AM -0700, Daniel Colascione wrote:
> > > > > On Wed, May 22, 2019 at 7:52 AM Christian Brauner <christian@brauner.io> wrote:
> > > > > > I'm not going to go into yet another long argument. I prefer pidfd_*.
> > > > >
> > > > > Ok. We're each allowed our opinion.
> > > > >
> > > > > > It's tied to the api, transparent for userspace, and disambiguates it
> > > > > > from process_vm_{read,write}v that both take a pid_t.
> > > > >
> > > > > Speaking of process_vm_readv and process_vm_writev: both have a
> > > > > currently-unused flags argument. Both should grow a flag that tells
> > > > > them to interpret the pid argument as a pidfd. Or do you support
> > > > > adding pidfd_vm_readv and pidfd_vm_writev system calls? If not, why
> > > > > should process_madvise be called pidfd_madvise while process_vm_readv
> > > > > isn't called pidfd_vm_readv?
> > > >
> > > > Actually, you should then do the same with process_madvise() and give it
> > > > a flag for that too if that's not too crazy.
> > >
> > > I don't know what you mean. My gut feeling is that for the sake of
> > > consistency, process_madvise, process_vm_readv, and process_vm_writev
> > > should all accept a first argument interpreted as either a numeric PID
> > > or a pidfd depending on a flag --- ideally the same flag. Is that what
> > > you have in mind?
> >
> > Yes. For the sake of consistency they should probably all default to
> > interpret as pid and if say PROCESS_{VM_}PIDFD is passed as flag
> > interpret as pidfd.
> 
> Sounds good to me!

Then, I want to change from pidfd to pid at next revsion and stick to
process_madvise as naming. Later, you guys could define PROCESS_PIDFD
flag and change all at once every process_xxx syscall friends.

If you are faster so that I see PROCESS_PIDFD earlier, I am happy to
use it.

Thanks.