GNU bug report logs - #50339
master creashed in compact_small_strings

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 50339 in the body.
You can then email your comments to 50339 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: bug-gnu-emacs <at> gnu.org
Subject: master creashed in compact_small_strings
Date: Thu, 02 Sep 2021 12:04:34 -0400

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

Master from May 11 crashed in __memmove_ssse3, called from
compact_small_strings.  Is there any debugging I can do,
before that gdb session is lost when my laptop next crashes?

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #8 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: rms <at> gnu.org
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Thu, 02 Sep 2021 19:12:08 +0300

> From: Richard Stallman <rms <at> gnu.org>
> Date: Thu, 02 Sep 2021 12:04:34 -0400
> 
> Master from May 11 crashed in __memmove_ssse3, called from
> compact_small_strings.  Is there any debugging I can do,
> before that gdb session is lost when my laptop next crashes?

Can you tell why it crashed?  Which of the arguments to memmove were
bogus?

Message #11 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Sat, 04 Sep 2021 13:18:28 -0400

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > Can you tell why it crashed?  Which of the arguments to memmove were
  > bogus?

s is nonzero.  It is 0x555556fb4bc0.
from is 0x5555570edcc0

Is s supposed to be > from?

from->string is 0.  Strange.

size is 0x511be45adaa18398
nbytes is 0x511be45adaa1838d

That value of size was used to calculate from_end and to_end.

I am guessing how
to find out in GDB what the data at s says nbytes ought to be.
But s->u.s.size is 6.


-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #14 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: rms <at> gnu.org
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Sat, 04 Sep 2021 20:35:56 +0300

> From: Richard Stallman <rms <at> gnu.org>
> Cc: 50339 <at> debbugs.gnu.org
> Date: Sat, 04 Sep 2021 13:18:28 -0400
> 
> s is nonzero.  It is 0x555556fb4bc0.
> from is 0x5555570edcc0
> 
> Is s supposed to be > from?

No, I think it's supposed to be equal to from.

> from->string is 0.  Strange.

Yes, because s = from->string != 0.

> size is 0x511be45adaa18398
> nbytes is 0x511be45adaa1838d
> 
> That value of size was used to calculate from_end and to_end.

Look like bogus values.

Very strange.

Does anyone have any idea how this could happen?

Message #17 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Sun, 05 Sep 2021 23:08:11 -0400

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > > That value of size was used to calculate from_end and to_end.

  > Look like bogus values.

  > Very strange.

  > Does anyone have any idea how this could happen?

It could be a random hardware failure.
Such things have happened.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #20 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: rms <at> gnu.org
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Mon, 06 Sep 2021 08:42:49 +0300

> From: Richard Stallman <rms <at> gnu.org>
> Cc: 50339 <at> debbugs.gnu.org
> Date: Sun, 05 Sep 2021 23:08:11 -0400
> 
>   > Look like bogus values.
> 
>   > Very strange.
> 
>   > Does anyone have any idea how this could happen?
> 
> It could be a random hardware failure.
> Such things have happened.

Yes, that's one thing that crossed my mind.  Did you have hardware
problems on this machine in the past?

Message #23 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Mon, 06 Sep 2021 23:17:39 -0400

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > Yes, that's one thing that crossed my mind.  Did you have hardware
  > problems on this machine in the past?

Yes, though I don't know if they involved incorrect execution on the CPU.
I have no evidence for that specific kind of problem.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #26 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: rms <at> gnu.org
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Tue, 07 Sep 2021 09:14:19 +0300

> From: Richard Stallman <rms <at> gnu.org>
> Cc: 50339 <at> debbugs.gnu.org
> Date: Mon, 06 Sep 2021 23:17:39 -0400
> 
>   > Yes, that's one thing that crossed my mind.  Did you have hardware
>   > problems on this machine in the past?
> 
> Yes, though I don't know if they involved incorrect execution on the CPU.
> I have no evidence for that specific kind of problem.

A memory-related problem could also explain that.

Message #29 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: eliz <at> gnu.org, 50339 <at> debbugs.gnu.org
Cc: rms <at> gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Tue, 07 Sep 2021 23:27:17 -0400

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

Alas, my machine crashed and that session was lost.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #32 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: Richard Stallman <rms <at> gnu.org>
Cc: eliz <at> gnu.org, 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Sun, 19 Sep 2021 09:05:17 -0700

Richard Stallman <rms <at> gnu.org> writes:

> Alas, my machine crashed and that session was lost.

Should this bug remain open, or does that preclude us making any further
progress here?  I can see that you discussed that this might have been
caused by a hardware issue.

Message #35 received at 50339 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: 50339 <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Mon, 20 Sep 2021 19:48:22 -0400

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > > Alas, my machine crashed and that session was lost.

  > Should this bug remain open, or does that preclude us making any further
  > progress here?

I can't do any further debugging on the process which crashed.
So I can't contribute any further for the moment.
Whether to close the ticket isup to you.

  >   I can see that you discussed that this might have been
  > caused by a hardware issue.

That was just speculation, of course.  But I could not see how obeying
the instructions in that code could have produced this result.

Perhaps a bug in a signal handler could have done it.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #40 received at 50339-done <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: rms <at> gnu.org
Cc: 50339-done <at> debbugs.gnu.org
Subject: Re: bug#50339: master creashed in compact_small_strings
Date: Tue, 21 Sep 2021 00:41:37 -0700

Richard Stallman <rms <at> gnu.org> writes:

>   > > Alas, my machine crashed and that session was lost.
>
>   > Should this bug remain open, or does that preclude us making any further
>   > progress here?
>
> I can't do any further debugging on the process which crashed.
> So I can't contribute any further for the moment.
> Whether to close the ticket isup to you.
>
>   >   I can see that you discussed that this might have been
>   > caused by a hardware issue.
>
> That was just speculation, of course.  But I could not see how obeying
> the instructions in that code could have produced this result.
>
> Perhaps a bug in a signal handler could have done it.

OK, let's close it for now then, under the assumption that there is not
much we can do to make any progress here given that the session was
lost.

I suppose that our best chance to catch it, if it is indeed a bug in our
code, would be for someone to run into this crash again.  For better or
for worse.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.