Public bug reported:
I am seeing sporadic (but relatively repeatable) crashes in a g++/QEMU
build environment (building on amd64, targeting arm64) when our Ubuntu
kernel was updated from 6.8.0-1019.21~22.04.1 to 6.8.0-1021.23~22.04.1.
While I am not 100% sure that the kernel is to blame, I do know that
everything worked fine with ubuntu/images/hvm-ssd/ubuntu-
jammy-22.04-${arch}-server-20241211, and it broke with
ubuntu/images/hvm-ssd/ubuntu-jammy-22.04-${arch}-server-20241217. After
doing some research, it seems to me that the kernel update is the most
likely culprit.
This kernel commit [1] (Increase brk randomness entropy for 64-bit
systems, only 4 lines) was one of the many changes introduced in the
6.8.0-1020 AWS kernel update. This commit was identified as problematic
by two independent developers (both working with QEMU) reporting their
respective problems: [2] and [3]. Furthermore, this Linux kernel mailing
list thread [4] is the suggestion/recommendation to remove this patch
from "stable" kernel versions due to the risk that it breaks buggy
application software. In this case QEMU is the buggy software.
Supposedly, according to [5], the underlying QEMU bug was fixed in
upstream QEMU in version 8.1 [6], but Ubuntu 22.04 is stuck at 6.2.
I think the "Increase brk randomness entropy for 64-bit systems" patch
should be reverted since it breaks another Ubuntu-supported package
(QEMU 6.2).
[1] -
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b0cde867b80a5e81fcbc0383e138f5845f2005ee
[2] - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1085762
[3] -
https://www.mail-archive.com/debian-bugs-dist%40lists.debian.org/msg2001941.html
[4] - https://www.spinics.net/lists/stable/msg792373.html
[5] -
https://www.mail-archive.com/[email protected]/msg2001950.html
[6] -
https://github.com/qemu/qemu/commit/dd55885516f42f718d0d121c59a5f7be5fdae3e6
** Affects: linux-aws (Ubuntu)
Importance: Undecided
Status: New
** Description changed:
I am seeing sporadic (but relatively repeatable) crashes in a g++/QEMU
build environment (building on amd64, targeting arm64) when our Ubuntu
kernel was updated from 6.8.0-1019.21~22.04.1 to 6.8.0-1021.23~22.04.1.
While I am not 100% sure that the kernel is to blame, I do know that
everything worked fine with ubuntu/images/hvm-ssd/ubuntu-
jammy-22.04-${arch}-server-20241211, and it broke with
ubuntu/images/hvm-ssd/ubuntu-jammy-22.04-${arch}-server-20241217. After
doing some research, it seems to me that the kernel update is the most
likely culprit.
This kernel commit [1] (Increase brk randomness entropy for 64-bit
- systems, only 4 lines). This was one of the many changes introduced in
- the 6.8.0-1020 AWS kernel update. This commit was identified as
- problematic by two independent developers (both working with QEMU)
- reporting their respective problems: [2] and [3]. Furthermore, this
- Linux kernel mailing list thread [4] is the suggestion/recommendation to
- remove this patch from "stable" kernel versions due to the risk that it
- breaks buggy application software. In this case QEMU is the buggy
- software. Supposedly, according to [5], the underlying QEMU bug was
- fixed in upstream QEMU in version 8.1 [6], but Ubuntu 22.04 is stuck at
- 6.2.
+ systems, only 4 lines) was one of the many changes introduced in the
+ 6.8.0-1020 AWS kernel update. This commit was identified as problematic
+ by two independent developers (both working with QEMU) reporting their
+ respective problems: [2] and [3]. Furthermore, this Linux kernel mailing
+ list thread [4] is the suggestion/recommendation to remove this patch
+ from "stable" kernel versions due to the risk that it breaks buggy
+ application software. In this case QEMU is the buggy software.
+ Supposedly, according to [5], the underlying QEMU bug was fixed in
+ upstream QEMU in version 8.1 [6], but Ubuntu 22.04 is stuck at 6.2.
I think the "Increase brk randomness entropy for 64-bit systems" patch
should be reverted since it breaks another Ubuntu-supported package
(QEMU 6.2).
[1] -
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b0cde867b80a5e81fcbc0383e138f5845f2005ee
[2] - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1085762
[3] -
https://www.mail-archive.com/debian-bugs-dist%40lists.debian.org/msg2001941.html
[4] - https://www.spinics.net/lists/stable/msg792373.html
[5] -
https://www.mail-archive.com/[email protected]/msg2001950.html
[6] -
https://github.com/qemu/qemu/commit/dd55885516f42f718d0d121c59a5f7be5fdae3e6
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https://bugs.launchpad.net/bugs/2096782
Title:
Change in 22.04 kernel causes QEMU crashes
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