The search for available page flags

Among the many other things crammed into the page structure that is used to represent a page of memory in the kernel is a set of flags to track the state of the page. These flags have been in short supply for some time; LWN looked at the problem nearly ten years ago. Jérôme Glisse ran a session during the memory-management track of the 2019 Linux Storage, Filesystem, and Memory-Management Summit to explore ways of making some flags available for new uses. While there may be some easily available bits in the field that holds the page flags, obtaining a significant number of them may be tricky.

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