Engineers from Canonical have warned about regressions in the upcoming update of the kernel package 7.0.0-28.28, which will be delivered to users of Ubuntu 26.04 and Ubuntu 24.04. The regression manifests when using the amdgpu driver and leads to a significant decrease in the performance of certain applications utilizing the AMD ROCm stack. For instance, due to the regression, the execution time of the Stable Diffusion XL (SDXL) model using ComfyUI has slowed down by 42 times (from 9 seconds to 388 seconds).
The issue has been noted in the Linux kernel update 7.0.12, which serves as the basis for version 7.0.0-28.28 of the kernel package for Ubuntu. It is reported that the prepared update contains fixes for critical vulnerabilities, and Canonical cannot delay its release due to the noted regression; therefore, it has been decided to release it as is, with the regression addressed in the next corrective update. Users for whom the highlighted regression is more critical than the vulnerability fixes may choose not to upgrade to release 7.0.0-28.28 and wait for the next update.
The problem also occurs in kernel packages 7.0.12 released for Fedora, CachyOS, and other Linux distributions. The issue has been resolved in the kernel release 7.0.13. A workaround to eliminate the regression in ComfyUI can be achieved by using the flag '--disable-mmap'.
Source: opennet.ru
