From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
To: "Ludovic Courtès" <ludovic.courtes@inria.fr>
Cc: 54557@debbugs.gnu.org,
Philippe Swartvagher <philippe.swartvagher@inria.fr>
Subject: bug#54557: “fakechroot” execution engine doesn’t work for Bash
Date: Fri, 25 Mar 2022 23:03:13 -0400 [thread overview]
Message-ID: <878rsxxvny.fsf@gmail.com> (raw)
In-Reply-To: <87sfr79i9j.fsf@inria.fr> ("Ludovic Courtès"'s message of "Thu, 24 Mar 2022 22:02:00 +0100")
Hi Ludovic,
Ludovic Courtès <ludovic.courtes@inria.fr> writes:
[...]
> The message comes from ld.so. My guess is that the problem comes from
> Bash’s terrible ‘malloc’ replacement:
>
[...]
> [Time passes…] I confirmed this hypothesis by running:
>
> guix pack -RR -S /bin=bin -m manifest.scm
>
> on this manifest:
>
> (use-modules (guix) (guix utils)
> (guix profiles)
> (gnu packages bash))
>
> (define bash-sans-malloc
> (package/inherit bash
> (name "bash-sans-malloc")
> (arguments
> (substitute-keyword-arguments (package-arguments bash)
> ((#:configure-flags flags ''())
> `(cons "--without-bash-malloc" ,flags))))))
>
> (packages->manifest (list bash-sans-malloc))
>
>
> Works just fine:
>
> $ unshare -mrf sh -c 'mount -t tmpfs -o ro none /gnu/store; GUIX_EXECUTION_ENGINE=fakechroot /tmp/pack/bin/bash --version'
> GNU bash, version 5.1.8(1)-release (x86_64-unknown-linux-gnu)
> Copyright (C) 2020 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
[...]
> Perhaps we should build Bash ‘--without-bash-malloc’ unconditionally in
> ‘core-updates’? The ‘INSTALL’ file reads:
>
> '--with-bash-malloc'
> Use the Bash version of 'malloc' in the directory 'lib/malloc'.
> This is not the same 'malloc' that appears in GNU libc, but an
> older version originally derived from the 4.2 BSD 'malloc'. This
> 'malloc' is very fast, but wastes some space on each allocation.
> This option is enabled by default. The 'NOTES' file contains a
> list of systems for which this should be turned off, and
> 'configure' disables this option automatically for a number of
> systems.
>
> There might be other options if we want to keep it, such as changing the
> ELF visibility of those symbols, but I wonder if it’s worth the effort.
>
> Thoughts?
I'd be OK with --without-bash-malloc; it seems we'll pay a bit in terms
of Bash performance in exchange for better memory usage. It also brings
benefits such as solving this issue and may benefit from
advances/bugfixes to glibc's malloc in the future, if there are any.
Well done investigating!
Maxim
next prev parent reply other threads:[~2022-03-26 3:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-24 21:02 bug#54557: “fakechroot” execution engine doesn’t work for Bash Ludovic Courtès
2022-03-25 10:16 ` Philippe SWARTVAGHER
2022-03-28 6:59 ` Ludovic Courtès
2022-03-26 3:03 ` Maxim Cournoyer [this message]
2022-03-28 10:06 ` Ludovic Courtès
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