Public bug reported: SRU Justification
[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 bug requests that multi-gen LRU be built into the kernel, but be 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 this 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. [Other] PIT: 421036236 ** Affects: linux-gke (Ubuntu) Importance: Undecided Status: New ** Affects: linux-gke (Ubuntu Noble) Importance: Undecided Status: New ** Also affects: linux-gke (Ubuntu) Importance: Undecided Status: New ** No longer affects: linux-gcp (Ubuntu) ** Also affects: linux-gke (Ubuntu Noble) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-gcp in Ubuntu. https://bugs.launchpad.net/bugs/2113905 Title: Compile multi-gen LRU in kernel but keep it disabled by default Status in linux-gke package in Ubuntu: New Status in linux-gke source package in Noble: New Bug description: SRU Justification [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 bug requests that multi-gen LRU be built into the kernel, but be 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 this 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. [Other] PIT: 421036236 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-gke/+bug/2113905/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
