[$] More timing side-channels for the page cache

In 2019, researchers published a way to
identify which file-backed pages
were being accessed on a system using timing information from the page cache,
leading to a handful of unpleasant consequences and a change to the design of
the

mincore() system call. Discussion at the time
led to a number of ad-hoc patches to address the
problem. The lack of new page-cache attacks suggested that attempts to fix
things in a piecemeal fashion had succeeded. Now, however, Sudheendra Raghav Neela,
Jonas Juffinger, Lukas Maar, and Daniel Gruss have
found a new set of
holes in the Linux kernel’s page-cache-timing protections that allow
the same general class of attack.