CyberRota Analysis
AI-GeneratedThe vulnerability in the Linux kernel affects the NFS subsystem, where the accounting for unstable writes is incorrectly calculated based on the size of the folio rather than the actual request size. This can lead to significant overcharging of writeback memory, potentially overwhelming the system's dirty threshold and throttling all buffered writers, including unrelated NFS server threads. System administrators managing Linux environments with NFS should prioritize addressing this issue to prevent performance degradation and ensure stable operation under heavy load scenarios.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: NFS: Charge unstable writes by request size, not folio size nfs_folio_mark_unstable() and nfs_folio_clear_commit() charge and uncharge NR_WRITEBACK/WB_WRITEBACK by folio_nr_pages(folio) once per *request* added to or removed from a commit list. This is correct only when a folio has a single associated request. When pg_test splits a folio into N sub-folio requests (e.g. pNFS flexfiles striping with a stripe unit smaller than the folio size, or plain wsize-limited splitting), each of the N requests independently charges the whole folio's page count, inflating the accounting by a factor of N per folio. With large folios and small stripe units this reaches multiple orders of magnitude: a 2 MiB folio split into 512 4 KiB requests can charge up to 512x its real size, pushing global dirty+writeback accounting past the system's dirty threshold and forcing every buffered writer on the host into the hard-throttle path, including unrelated in-kernel NFS server threads sharing the box. Charge each request only for the pages it actually covers.