This bug is awaiting verification that the linux- oracle-6.14/6.14.0-1007.7~24.04.1 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-noble-linux- oracle-6.14' to 'verification-done-noble-linux-oracle-6.14'. If the problem still exists, change the tag 'verification-needed-noble-linux- oracle-6.14' to 'verification-failed-noble-linux-oracle-6.14'.
If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: kernel-spammed-noble-linux-oracle-6.14-v2 verification-needed-noble-linux-oracle-6.14 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2110289 Title: snapd has high CPU usage for exactly 150 seconds every 5, 7.5 or 10 minutes Status in Go: Invalid Status in Linux: Fix Committed Status in snapd: Invalid Status in linux package in Ubuntu: Fix Released Status in linux source package in Plucky: Fix Committed Bug description: SRU Justification: [Impact] fs/eventpoll: fix endless busy loop after timeout has expired commit 0a65bc27bd64 introduced a regression where if the epoll time-out is too small and ep_poll(...) is entered after the time-out already reached, the kernel will soft-lock itself due to improper time-out handling. [Fix] Plucky: cherry-picked from upstream stable linux-6.14.y Oracular: not affected Noble: not affected Jammy: not affected Focal: not affected Bionic: not affected Xenial: not affected Trusty: not affected [Test Plan] * Use the provided reproducer to check if the test program will cause high CPU usage. * Check if snapd still causes high CPU usage every 5 minutes. [Where problems could occur] The change involves fixing the timed-out handling logic when the timer expires before the event is processed in the wait queue. This may cause epoll-related issues if the fix is found to be inappropriate. [Notes] Oracular and below are not affected, as the commit introduced regression was not present in older kernels or their stable trees. [Original Description] Since recently, I have observed a periodic high CPU spike on the snapd process. It first occurs 5 minutes after start of the snapd systemd service. It always lasts for exactly 150 seconds (2.5 minutes) and occurs every 5, 7.5 or 10 minutes. It maxes out a CPU core for the 150 seconds it is running. If you run `sudo snap refresh` while the CPU spike is occurring, the spike stops immediately. I have attached a CPU usage log which logs the CPU usage of the snapd process every 5 seconds. Some info about my system: snap --version: snap 2.68.4 snapd 2.68.4 series 16 ubuntu 22.04 kernel 6.14.5-1-liquorix-amd64 lsb_release -a: Distributor ID: Ubuntu Description: Ubuntu 22.04.5 LTS Release: 22.04 Codename: jammy uname -a: Linux schneeflocke 6.14.5-1-liquorix-amd64 #1 ZEN SMP PREEMPT_DYNAMIC liquorix 6.14-7ubuntu1~jammy (2025-05 x86_64 x86_64 x86_64 GNU/Linux Measurements: Spike Start - Spike End -> Total Time 12:25:26 - 12:22:56 -> 2:30 min 12:35:26 - 12:37:56 -> 2:30 min 12:40:26 - 12:42:56 -> 2:30 min 12:47:56 - 12:50:26 -> 2:30 min 12:52:56 - 12:55:26 -> 2:30 min What additional info can I provide to identify the problem? To manage notifications about this bug go to: https://bugs.launchpad.net/golang/+bug/2110289/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
