Public bug reported: [Impact]
During our AWS testing we were able to trigger some hibernation failures in some Xen instance types. One problem is a kernel panic in the resume callback of the xen-netfront driver. A workaround to this problem is to compile the driver as a module and reload it at resume (we were already doing this reload with the bionic kernel that had this driver compiled as a module, but for some reasons eoan and focal had this statically compiled). Other issues were showing up as hangs on resume, these seem to be prevented by using the new Xen/hibernation patch set posted by Anchal to the LKML: https://lore.kernel.org/lkml/cover.1589926004.git.ancha...@amazon.com/ This new patch set is still being reviewed, but according to our tests it really seems to fix some of these hangs on resume. In addition to that we can improve hibernation reliability and performance even more by applying the updated swapoff optimization patch (that has been merged upstream). [Test case] Create a Xen instance in AWS, hibernate/resume multiple times. [Fix] The following set of fixes can be used to improve hibernation performance and reliability: - new Xen/hibernation patch set from the LKML (see link above) - config change to compile xen-netfront as a module - new swapoff optimization patch [Regression potential] The xen-netfront config change and the new swapoff optimization patch are pretty safe (one is a config change that affects only the xen- netfront driver, the other is a clean cherry-pick of an upstream commit). The new Xen/hibernation update is pretty big and the new patches are still under review, however according to our tests it really seems to fix some of the hang issues (it definitely makes things better). Moreover, all the changes are affecting Xen and they are restricted to the hibernation/resume code paths, so, in conclusion, the overall regression potential is minimal. [See also] NOTE: the fix mentioned in LP: #1879711 (disable CONFIG_DMA_CMA) was also applied during our tests and it is also required to make hibernation stable in Xen. ** Affects: linux-aws (Ubuntu) Importance: High Assignee: Andrea Righi (arighi) Status: New ** Affects: linux-aws (Ubuntu Eoan) Importance: High Assignee: Andrea Righi (arighi) Status: New ** Affects: linux-aws (Ubuntu Focal) Importance: High Assignee: Andrea Righi (arighi) Status: New ** Also affects: linux-aws (Ubuntu Focal) Importance: Undecided Status: New ** Also affects: linux-aws (Ubuntu Eoan) Importance: Undecided Status: New ** Changed in: linux-aws (Ubuntu Eoan) Importance: Undecided => High ** Changed in: linux-aws (Ubuntu Focal) Importance: Undecided => High ** Changed in: linux-aws (Ubuntu Focal) Assignee: (unassigned) => Andrea Righi (arighi) ** Changed in: linux-aws (Ubuntu Eoan) Assignee: (unassigned) => Andrea Righi (arighi) ** Changed in: linux-aws (Ubuntu) Assignee: (unassigned) => Andrea Righi (arighi) ** Changed in: linux-aws (Ubuntu) Importance: Undecided => High -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1881869 Title: linux-aws: fix Xen / hibernation issues To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-aws/+bug/1881869/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
