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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jann Horn <jannh@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Alan Stern <stern@rowland.harvard.edu>,
	 Andrea Parri <parri.andrea@gmail.com>,
	Will Deacon <will@kernel.org>,
	 Peter Zijlstra <peterz@infradead.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	 Nicholas Piggin <npiggin@gmail.com>,
	David Howells <dhowells@redhat.com>,
	 Jade Alglave <j.alglave@ucl.ac.uk>,
	Luc Maranget <luc.maranget@inria.fr>,
	 "Paul E. McKenney" <paulmck@kernel.org>,
	Akira Yokosawa <akiyks@gmail.com>,
	 Daniel Lustig <dlustig@nvidia.com>,
	Adam Zabrocki <pi3@pi3.com.pl>,
	 kernel list <linux-kernel@vger.kernel.org>,
	 Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Oleg Nesterov <oleg@redhat.com>,
	 Andy Lutomirski <luto@amacapital.net>,
	Bernd Edlinger <bernd.edlinger@hotmail.de>,
	 Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	 stable <stable@vger.kernel.org>, Marco Elver <elver@google.com>,
	 Dmitry Vyukov <dvyukov@google.com>,
	kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: [PATCH] signal: Extend exec_id to 64bits
Date: Wed, 1 Apr 2020 19:05:59 -0700	[thread overview]
Message-ID: <CAHk-=whks0iE1f=Ka0_vo2PYg774P7FA8Y30YrOdUBGRH-ch9A@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez1f82re_V=DzQuRHpy7wOWs1iixrah4GYYxngF1v-moZw@mail.gmail.com>

On Wed, Apr 1, 2020 at 6:36 PM Jann Horn <jannh@google.com> wrote:
>
> Since the read is already protected by the tasklist_lock, an
> alternative might be to let the execve path also take that lock to
> protect the sequence number update,

No.

tasklist_lock is aboue the hottest lock there is in all of the kernel.

We're not doing stupid things for theoretical issues.

Stop this crazy argument.

A comment - sure. 64-bit atomics or very expensive locks? Not a chance.

                   Linus

  reply	other threads:[~2020-04-02  2:06 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 21:50 Curiosity around 'exec_id' and some problems associated with it Adam Zabrocki
2020-03-29 22:43 ` Kees Cook
2020-03-30  8:34   ` Oleg Nesterov
2020-03-31  4:29   ` Adam Zabrocki
2020-04-01 20:47   ` [PATCH] signal: Extend exec_id to 64bits Eric W. Biederman
2020-04-01 20:55     ` Linus Torvalds
2020-04-01 21:03       ` Eric W. Biederman
2020-04-01 23:37     ` Jann Horn
2020-04-01 23:51       ` Linus Torvalds
2020-04-01 23:55         ` Linus Torvalds
2020-04-02  1:35           ` Jann Horn
2020-04-02  2:05             ` Linus Torvalds [this message]
2020-04-02 13:11               ` Eric W. Biederman
2020-04-02 18:06                 ` Linus Torvalds
2020-04-02  4:46     ` Jann Horn
2020-04-02 14:14       ` Eric W. Biederman
2020-04-03  2:11       ` Adam Zabrocki
2020-04-02  7:19     ` Kees Cook
2020-04-02  7:22     ` Bernd Edlinger

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