On 01.02.25 03:15, Sourav Panda wrote:
Hi,
Hi,
KSM is a powerful tool for deduplicating memory, reducing usage by merging
identical pages across processes. However, there are certain interface and
implementation aspect that prevents its deployment in our use case; wherein
security and efficiency (CPU overhead - due to background scanning) are of
greater importance.
We propose Selective KSM, a mechanism to control when the merging takes
place and what pages can be merged together. We do this by partitioning the
merge-space as per security-domains and carryout the merging as part of a
synchronous syscall. Doing so, we ensure sensitive-content is not merged
with non-sensitive content.
I'll note that there was an RFC for uKSM [1] last year. Unfortunately, I
didn't have time to look into it in more detail, and there was never any
push for it.
In particular, it proposed an interface:
- /proc/uksm/merge enables the merging of two pages given their process
IDs and addresses.
- /proc/uksm/unmerge allows unmerging a previously merged KSM page.
- /proc/uksm/cmp provides a lightweight mechanism to check page content
equivalence before invoking a merge operation.
[1]
https://lore.kernel.org/linux-mm/20240329104035.62942-1-teawater@xxxxxxxxxxxx/T/
--
Cheers,
David / dhildenb
