[SRU][N:linux-gke][PATCH v2 0/1] Compile multi-gen LRU in kernel but keep it disabled by default

[Ian Whitfield]

BugLink: https://bugs.launchpad.net/bugs/2113905

[Impact]
Google has previously requested multi-gen LRU to be disabled due to a bug (see
https://bugs.launchpad.net/bugs/2084716), however, this prevents customers from
opting into usage of multi-gen LRU at all.

This patchset builds multi-gen LRU into the kernel, but disabled by default,
such that users can opt-in as needed.

[Fix]
Set CONFIG_LRU_GEN=y and CONFIG_LRU_GEN_ENABLED=n.

[Test Plan]
Google has provided the expected output:
$ cat /boot/config-$(uname -r) | grep LRU
CONFIG_LRU_GEN=y
# CONFIG_LRU_GEN_ENABLED is not set
# CONFIG_LRU_GEN_STATS is not set

Based on the docs here:
https://docs.kernel.org/next/admin-guide/mm/multigen_lru.html
You can also check this module is available but disabled by verifying the output:
$ cat /sys/kernel/mm/lru_gen/enabled
0x0000

[Where problems could occur]
The only expected change in behavior is that multi-gen LRU is available for
customers, but the default behavior should be identical. By having this module
available, it's possible that the bug responsible for originally disabling
multi-gen LRU could come up again, but it should only impact customers that
opt-in.

v2: Added description of the change to the commit message.

Ian Whitfield (1):
  UBUNTU: [Config] gke: Build multi-gen LRU but leave it disabled

 debian.gke/config/annotations | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

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2.43.0