Re: [patch 1/2] x86_64 page fault NMI-safe

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From: Linus Torvalds
Date: Thursday, July 15, 2010 - 9:49 am

On Thu, Jul 15, 2010 at 9:44 AM, Mathieu Desnoyers
<mathieu.desnoyers@efficios.com> wrote:

No, that can never happen.

Why? Simple: regular interrupts aren't ever enabled in eflags. So the
only kinds of traps we can get are NMI's (that don't follow the normal
rules), and exceptions.

Of course, if there is some trap that re-enables interrupts even if
the trap happened in an interrupt-disabled region, then that would
change things, but that would be a bad bug regardless (and totally
independently of any NMI issues). So in that sense it's a "could
happen", but it's something that would be a totally separate bug.

                    Linus
--
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Messages in current thread:
[patch 0/2] x86: NMI-safe trap handlers, Mathieu Desnoyers, (Wed Jul 14, 8:49 am)
[patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 8:49 am)
[patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Wed Jul 14, 8:49 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 9:28 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Maciej W. Rozycki, (Wed Jul 14, 9:42 am)
Re: [patch 0/2] x86: NMI-safe trap handlers, Andi Kleen, (Wed Jul 14, 10:06 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 10:06 am)
Re: [patch 0/2] x86: NMI-safe trap handlers, Mathieu Desnoyers, (Wed Jul 14, 10:08 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 11:10 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Wed Jul 14, 11:12 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Ingo Molnar, (Wed Jul 14, 11:46 am)
Re: [patch 0/2] x86: NMI-safe trap handlers, Andi Kleen, (Wed Jul 14, 11:56 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 12:14 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Maciej W. Rozycki, (Wed Jul 14, 12:21 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Wed Jul 14, 12:36 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 12:41 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 12:54 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Andi Kleen, (Wed Jul 14, 12:56 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Wed Jul 14, 12:58 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 1:05 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Andi Kleen, (Wed Jul 14, 1:07 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, H. Peter Anvin, (Wed Jul 14, 1:08 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 1:17 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Maciej W. Rozycki, (Wed Jul 14, 1:36 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 1:39 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 1:55 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Ingo Molnar, (Wed Jul 14, 2:18 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 2:23 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Maciej W. Rozycki, (Wed Jul 14, 2:45 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 2:52 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Wed Jul 14, 3:14 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 3:21 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 3:31 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Maciej W. Rozycki, (Wed Jul 14, 3:31 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Wed Jul 14, 3:31 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 3:37 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Wed Jul 14, 3:48 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Jeremy Fitzhardinge, (Wed Jul 14, 3:51 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 3:56 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 4:02 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Andi Kleen, (Wed Jul 14, 4:09 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Jul 14, 4:11 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 4:22 pm)
Re: [patch 0/2] x86: NMI-safe trap handlers, Tejun Heo, (Wed Jul 14, 4:29 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Tejun Heo, (Wed Jul 14, 4:32 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Wed Jul 14, 4:38 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Steven Rostedt, (Wed Jul 14, 4:40 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Jeremy Fitzhardinge, (Wed Jul 14, 4:54 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 6:23 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Wed Jul 14, 6:45 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Thu Jul 15, 7:11 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Andi Kleen, (Thu Jul 15, 7:35 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Steven Rostedt, (Thu Jul 15, 7:46 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 7:51 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 8:38 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Jul 15, 9:26 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Jul 15, 9:44 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 9:49 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Jul 15, 10:38 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Jul 15, 11:31 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 11:43 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 11:48 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, H. Peter Anvin, (Thu Jul 15, 1:44 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Jul 15, 3:01 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 3:16 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, H. Peter Anvin, (Thu Jul 15, 3:24 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 3:26 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Jul 15, 3:30 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, H. Peter Anvin, (Thu Jul 15, 3:46 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Andi Kleen, (Thu Jul 15, 3:58 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, H. Peter Anvin, (Thu Jul 15, 4:20 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 4:23 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, H. Peter Anvin, (Thu Jul 15, 4:41 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Thu Jul 15, 4:44 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, H. Peter Anvin, (Thu Jul 15, 4:46 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Andi Kleen, (Thu Jul 15, 4:48 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Fri Jul 16, 3:47 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Fri Jul 16, 4:21 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Steven Rostedt, (Fri Jul 16, 4:43 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Fri Jul 16, 5:00 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 5:28 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Steven Rostedt, (Fri Jul 16, 5:54 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Fri Jul 16, 7:49 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Andi Kleen, (Fri Jul 16, 8:34 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Fri Jul 16, 8:40 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 9:47 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Fri Jul 16, 9:58 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 10:54 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, H. Peter Anvin, (Fri Jul 16, 11:05 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 11:15 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, H. Peter Anvin, (Fri Jul 16, 11:17 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Fri Jul 16, 11:22 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Linus Torvalds, (Fri Jul 16, 11:25 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 11:28 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 11:32 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Linus Torvalds, (Fri Jul 16, 11:37 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Fri Jul 16, 12:13 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 12:26 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Andi Kleen, (Fri Jul 16, 12:28 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, H. Peter Anvin, (Fri Jul 16, 12:29 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Andi Kleen, (Fri Jul 16, 12:30 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 12:32 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Andi Kleen, (Fri Jul 16, 12:32 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Andi Kleen, (Fri Jul 16, 12:34 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Fri Jul 16, 12:39 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Linus Torvalds, (Fri Jul 16, 2:39 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Andi Kleen, (Fri Jul 16, 3:07 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Linus Torvalds, (Fri Jul 16, 3:26 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Mathieu Desnoyers, (Fri Jul 16, 3:40 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Andi Kleen, (Fri Jul 16, 3:41 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Linus Torvalds, (Fri Jul 16, 6:15 pm)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Sun Jul 18, 2:23 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Avi Kivity, (Sun Jul 18, 2:26 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Avi Kivity, (Sun Jul 18, 4:03 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Sun Jul 18, 10:36 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Avi Kivity, (Sun Jul 18, 11:04 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Sun Jul 18, 11:17 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Sun Jul 18, 11:22 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Steven Rostedt, (Sun Jul 18, 11:43 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Sun Jul 18, 12:26 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Avi Kivity, (Mon Jul 19, 12:32 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Tue Aug 3, 10:18 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Tue Aug 3, 11:25 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Tue Aug 3, 11:56 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Tue Aug 3, 12:45 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Linus Torvalds, (Tue Aug 3, 1:02 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Ingo Molnar, (Tue Aug 3, 1:10 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Ingo Molnar, (Tue Aug 3, 1:21 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Tue Aug 3, 1:54 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Tue Aug 3, 2:16 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Tue Aug 3, 11:27 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Dave Chinner, (Tue Aug 3, 11:46 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Tue Aug 3, 11:46 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Ingo Molnar, (Wed Aug 4, 12:14 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Ingo Molnar, (Wed Aug 4, 12:21 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, Peter Zijlstra, (Wed Aug 4, 2:46 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Aug 4, 7:06 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Wed Aug 4, 7:45 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Wed Aug 4, 7:50 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Wed Aug 4, 7:56 am)
Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault, H. Peter Anvin, (Wed Aug 4, 1:23 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Aug 5, 6:42 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Thu Aug 5, 6:49 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Masami Hiramatsu, (Thu Aug 5, 11:18 pm)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Fri Aug 6, 2:50 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Fri Aug 6, 2:51 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Fri Aug 6, 3:11 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Peter Zijlstra, (Fri Aug 6, 4:14 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Fri Aug 6, 6:37 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Fri Aug 6, 6:46 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Fri Aug 6, 7:13 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Fri Aug 6, 7:15 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Masami Hiramatsu, (Sat Aug 7, 2:51 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Frederic Weisbecker, (Mon Aug 9, 9:53 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Steven Rostedt, (Wed Aug 11, 7:34 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Steven Rostedt, (Wed Aug 11, 7:44 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Sun Aug 15, 6:35 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Avi Kivity, (Sun Aug 15, 9:33 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Sun Aug 15, 9:44 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Avi Kivity, (Sun Aug 15, 9:51 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Mathieu Desnoyers, (Sun Aug 15, 11:31 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Avi Kivity, (Mon Aug 16, 3:49 am)
Re: [patch 1/2] x86_64 page fault NMI-safe, Avi Kivity, (Mon Aug 16, 4:29 am)