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From: Florian Weimer <fweimer@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jann Horn <jannh@google.com>, Kevin Easton <kevin@guarana.org>,
	Andy Lutomirski <luto@kernel.org>,
	Christian Brauner <christian@brauner.io>,
	Aleksa Sarai <cyphar@cyphar.com>,
	"Enrico Weigelt, metux IT consult" <lkml@metux.net>,
	Al Viro <viro@zeniv.linux.org.uk>,
	David Howells <dhowells@redhat.com>,
	Linux API <linux-api@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Kees Cook <keescook@chromium.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Daniel Colascione <dancol@goo>
Subject: Re: RFC: on adding new CLONE_* flags [WAS Re: [PATCH 0/4] clone: add CLONE_PIDFD]
Date: Mon, 29 Apr 2019 22:38:06 +0200	[thread overview]
Message-ID: <87zho8bl8x.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <CAHk-=wi_N81mKYFz33ycoWiL7_tGbZBMJOsAs16inYzSza+OEw@mail.gmail.com> (Linus Torvalds's message of "Mon, 29 Apr 2019 13:21:06 -0700")

* Linus Torvalds:

> On Mon, Apr 29, 2019 at 12:55 PM Jann Horn <jannh@google.com> wrote:
>>
>> ... I guess that already has a name, and it's called vfork(). (Well,
>> except that the Linux vfork() isn't a real vfork().)
>
> What?
>
> Linux vfork() is very much a real vfork(). What do you mean?

In Linux-as-the-ABI (as opposed to Linux-as-the-implementation), vfork
is sometimes implemented as fork, so applications cannot rely on the
vfork behavior regarding the stopped parent and the shared address
space.

In fact, it would be nice to have a flag we can check in the posix_spawn
implementation, so that we can support vfork-as-fork without any run
time cost to native Linux.

Thanks,
Florian

WARNING: multiple messages have this Message-ID (diff)
From: Florian Weimer <fweimer@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jann Horn <jannh@google.com>, Kevin Easton <kevin@guarana.org>,
	Andy Lutomirski <luto@kernel.org>,
	Christian Brauner <christian@brauner.io>,
	Aleksa Sarai <cyphar@cyphar.com>, "Enrico Weigelt\,
	metux IT consult" <lkml@metux.net>,
	Al Viro <viro@zeniv.linux.org.uk>,
	David Howells <dhowells@redhat.com>,
	Linux API <linux-api@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Kees Cook <keescook@chromium.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Daniel Colascione <dancol@google.com>
Subject: Re: RFC: on adding new CLONE_* flags [WAS Re: [PATCH 0/4] clone: add CLONE_PIDFD]
Date: Mon, 29 Apr 2019 22:38:06 +0200	[thread overview]
Message-ID: <87zho8bl8x.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <CAHk-=wi_N81mKYFz33ycoWiL7_tGbZBMJOsAs16inYzSza+OEw@mail.gmail.com> (Linus Torvalds's message of "Mon, 29 Apr 2019 13:21:06 -0700")

* Linus Torvalds:

> On Mon, Apr 29, 2019 at 12:55 PM Jann Horn <jannh@google.com> wrote:
>>
>> ... I guess that already has a name, and it's called vfork(). (Well,
>> except that the Linux vfork() isn't a real vfork().)
>
> What?
>
> Linux vfork() is very much a real vfork(). What do you mean?

In Linux-as-the-ABI (as opposed to Linux-as-the-implementation), vfork
is sometimes implemented as fork, so applications cannot rely on the
vfork behavior regarding the stopped parent and the shared address
space.

In fact, it would be nice to have a flag we can check in the posix_spawn
implementation, so that we can support vfork-as-fork without any run
time cost to native Linux.

Thanks,
Florian

  reply	other threads:[~2019-04-29 20:38 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-14 20:14 [PATCH 0/4] clone: add CLONE_PIDFD Christian Brauner
2019-04-14 20:14 ` [PATCH 1/4] Make anon_inodes unconditional Christian Brauner
2019-04-14 20:14 ` [PATCH 2/4] clone: add CLONE_PIDFD Christian Brauner
2019-04-15 10:52   ` Oleg Nesterov
2019-04-15 11:42     ` Christian Brauner
2019-04-15 13:24       ` Oleg Nesterov
2019-04-15 13:52         ` Christian Brauner
2019-04-15 16:25           ` Joel Fernandes
2019-04-15 17:15         ` Jonathan Kowalski
2019-04-15 19:39           ` Daniel Colascione
2019-04-14 20:14 ` [PATCH 3/4] signal: support CLONE_PIDFD with pidfd_send_signal Christian Brauner
2019-04-14 20:14 ` [PATCH 4/4] samples: show race-free pidfd metadata access Christian Brauner
2019-04-15 10:08 ` RFC: on adding new CLONE_* flags [WAS Re: [PATCH 0/4] clone: add CLONE_PIDFD] Enrico Weigelt, metux IT consult
2019-04-15 15:50   ` Serge E. Hallyn
2019-04-16 18:32     ` Enrico Weigelt, metux IT consult
2019-04-29 15:49       ` Serge E. Hallyn
2019-04-29 17:31         ` Enrico Weigelt, metux IT consult
2019-05-05  2:32           ` Serge E. Hallyn
2019-04-15 19:59   ` Aleksa Sarai
2019-04-15 20:29     ` Andy Lutomirski
2019-04-15 21:27       ` Jonathan Kowalski
2019-04-15 23:58         ` Andy Lutomirski
2019-04-15 23:58           ` Andy Lutomirski
2019-04-16 18:45       ` Enrico Weigelt, metux IT consult
2019-04-16 21:31         ` Andy Lutomirski
2019-04-17 12:03           ` Enrico Weigelt, metux IT consult
2019-04-17 12:54             ` Christian Brauner
2019-04-18 15:46               ` Enrico Weigelt, metux IT consult
2019-04-17 12:19       ` Florian Weimer
2019-04-17 12:19         ` Florian Weimer
2019-04-17 16:46         ` Andy Lutomirski
2019-04-17 16:46           ` Andy Lutomirski
2019-04-20  7:14       ` Kevin Easton
2019-04-20 11:15         ` Christian Brauner
2019-04-20 15:06         ` Daniel Colascione
2019-04-29 19:30         ` Jann Horn
2019-04-29 19:55           ` Jann Horn
2019-04-29 20:21             ` Linus Torvalds
2019-04-29 20:38               ` Florian Weimer [this message]
2019-04-29 20:38                 ` Florian Weimer
2019-04-29 20:51                 ` Christian Brauner
2019-04-29 20:51                   ` Christian Brauner
2019-04-29 21:31                 ` Linus Torvalds
2019-04-29 21:31                   ` Linus Torvalds
2019-04-30  7:01                   ` Florian Weimer
2019-04-30  7:01                     ` Florian Weimer
2019-04-30  0:38               ` Jann Horn
2019-04-30  2:16                 ` Linus Torvalds
2019-04-30  8:21                   ` Florian Weimer
2019-04-30  8:21                     ` Florian Weimer
2019-04-30 16:19                     ` Linus Torvalds
2019-04-30 16:19                       ` Linus Torvalds
2019-04-30 16:26                       ` Linus Torvalds
2019-04-30 16:26                         ` Linus Torvalds
2019-04-30 17:07                         ` Florian Weimer
2019-04-30 17:07                           ` Florian Weimer
2019-04-30 12:39               ` Oleg Nesterov
2019-04-30 16:24                 ` Linus Torvalds
2019-04-29 20:49             ` Florian Weimer
2019-04-29 20:49               ` Florian Weimer
2019-04-29 20:52               ` Christian Brauner
2019-04-29 20:52                 ` Christian Brauner
2019-04-20 15:28       ` Al Viro
2019-04-16 18:37     ` Enrico Weigelt, metux IT consult
2019-04-15 10:16 ` [PATCH 0/4] clone: add CLONE_PIDFD Enrico Weigelt, metux IT consult

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