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From: Daniel Colascione <dancol@google.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Minchan Kim <minchan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	 LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	 Linux API <linux-api@vger.kernel.org>,
	oleksandr@redhat.com,  Suren Baghdasaryan <surenb@google.com>,
	Tim Murray <timmurray@google.com>,
	 Sandeep Patil <sspatil@google.com>,
	Sonny Rao <sonnyrao@google.com>,
	 Brian Geffon <bgeffon@google.com>,
	Michal Hocko <mhocko@suse.com>,
	 Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>,
	 John Dias <joaodias@google.com>
Subject: Re: [PATCH 2/4] mm: introduce external memory hinting API
Date: Mon, 13 Jan 2020 11:18:23 -0800
Message-ID: <CAKOZuevwbQvrFWqy5GOm4RXuGszKLBvRs9i-KbAi3nPcHhwvSw@mail.gmail.com> (raw)
In-Reply-To: <56ea0927-ad2e-3fbd-3366-3813330f6cec@virtuozzo.com>

On Mon, Jan 13, 2020, 12:47 AM Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
> > +SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start,
> > +             size_t, len_in, int, behavior, unsigned long, flags)
>
> I don't like the interface. The fact we have pidfd does not mean,
> we have to use it for new syscalls always. A user may want to set
> madvise for specific pid from console and pass pid as argument.
> pidfd would be an overkill in this case.
> We usually call "kill -9 pid" from console. Why shouldn't process_madvise()
> allow this?

All new APIs should use pidfds: they're better than numeric PIDs in
every way. If a program wants to allow users to specify processes by
numeric PID, it can parse that numeric PID, open the corresponding
pidfd, and then use that pidfd with whatever system call it wants.
It's not necessary to support numeric PIDs at the system call level to
allow a console program to identify a process by numeric PID.


  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 21:34 [PATCH 0/4] introduce memory hinting API for external process Minchan Kim
2020-01-10 21:34 ` [PATCH 1/4] mm: factor out madvise's core functionality Minchan Kim
2020-01-11  7:37   ` SeongJae Park
2020-01-13 18:11     ` Minchan Kim
2020-01-13 18:22       ` SeongJae Park
2020-01-10 21:34 ` [PATCH 2/4] mm: introduce external memory hinting API Minchan Kim
2020-01-11  7:34   ` SeongJae Park
2020-01-13 18:02     ` Minchan Kim
2020-01-13  8:47   ` Kirill Tkhai
2020-01-13 10:42     ` Christian Brauner
2020-01-13 18:44       ` Minchan Kim
2020-01-13 19:10         ` Christian Brauner
2020-01-13 19:27           ` Daniel Colascione
2020-01-13 20:42             ` Christian Brauner
2020-01-13 21:04               ` Daniel Colascione
2020-01-14 19:20                 ` Christian Brauner
2020-01-14 18:59           ` Minchan Kim
2020-01-14 19:22             ` Christian Brauner
2020-01-13 18:39     ` Minchan Kim
2020-01-13 19:18     ` Daniel Colascione [this message]
2020-01-14  8:39       ` Kirill Tkhai
2020-01-14 19:12         ` Minchan Kim
2020-01-15  9:38           ` Kirill Tkhai
2020-01-10 21:34 ` [PATCH 3/4] mm/madvise: employ mmget_still_valid for write lock Minchan Kim
2020-01-10 21:34 ` [PATCH 4/4] mm/madvise: allow KSM hints for remote API Minchan Kim
2020-01-11  7:42   ` SeongJae Park

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