Public bug reported:
When launching large arm64 instances on the focal or jammy ami, cma
allocation errors appear in the dmesg out:
[ 0.063255] cma: cma_alloc: reserved: alloc failed, req-size: 4096
pages, ret: -12
As far as I can tell, this does not impact instance launch in a
meaningful way, but I am unsure of the other implications of this. I was
able to confirm that these messages are only present in 5.15, as they do
not show up in the bionic image, and rolling back focal to linux-aws 5.4
avoids them as well.
This was present in at least 2 instance types and only appears to pop up
in large sizes (2x4 does not produce them, 64x124 (c6gn.16xlarge) does)
This could be as simple as just disabling CMA in the linux-aws pkg, as
it appears this is already the case in linux-azure(LP: #1949770).
Attaching dmesg out to the report.
# Replication
+ Launch a large arm64 instance (c6gn.16xlarge)
+ Observe the messages in kern.log / dmesg
** Affects: linux-aws (Ubuntu)
Importance: Undecided
Status: New
** Attachment added: "dmesg.txt"
https://bugs.launchpad.net/bugs/1990167/+attachment/5617126/+files/dmesg.txt
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https://bugs.launchpad.net/bugs/1990167
Title:
cma alloc failure in large 5.15 arm instances
Status in linux-aws package in Ubuntu:
New
Bug description:
When launching large arm64 instances on the focal or jammy ami, cma
allocation errors appear in the dmesg out:
[ 0.063255] cma: cma_alloc: reserved: alloc failed, req-size: 4096
pages, ret: -12
As far as I can tell, this does not impact instance launch in a
meaningful way, but I am unsure of the other implications of this. I
was able to confirm that these messages are only present in 5.15, as
they do not show up in the bionic image, and rolling back focal to
linux-aws 5.4 avoids them as well.
This was present in at least 2 instance types and only appears to pop
up in large sizes (2x4 does not produce them, 64x124 (c6gn.16xlarge)
does)
This could be as simple as just disabling CMA in the linux-aws pkg, as
it appears this is already the case in linux-azure(LP: #1949770).
Attaching dmesg out to the report.
# Replication
+ Launch a large arm64 instance (c6gn.16xlarge)
+ Observe the messages in kern.log / dmesg
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