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Move MADV_MERGEABLE part of ksm_madvise() into a dedicated helper since it will be further used for marking VMAs to be merged forcibly. This does not bring any functional changes. Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com>
Move MADV_UNMERGEABLE part of ksm_madvise() into a dedicated helper since it will be further used for unmerging VMAs forcibly. This does not bring any functional changes. Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com>
Yes, I know, this looks like a duplicate of `process_madvise()`. There are two reasons to do this, however: 1. implementing a new syscall is exceptionally easy and takes less code lines than ugly `/proc`-based API, although it imposes slightly more difficult usage onto userspace 2. the code gets actually much closer to be merged with `process_madvise()`, and this is a small step in that direction. So, basically, the `pmadv_ksm()` syscall is a twin of `process_madvise()`, but with two differences: 1. it works with MADV\_(UN)\?MERGEABLE hints only 2. it affects the whole address space of the target task The second difference is likely to disappear in case two syscalls are merged, but that's up to either me or to someone else to re-think how to do it. uksmd is already able to use this syscall. Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Present `pmadv_ksm()` syscall for all the arches. Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
As `pmadv_ksm()` syscall is out-of-tree, maintain a separate `/sys/kernel/pmadv/ksm` file with a syscall number so that userspace tools can always know what to use in runtime even if the syscall number shifts after adding another in-tree syscall. The idea is borrowed from futex2 submission. Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
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Rebased to #27 |
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Export patch series: https://github.com/kakra/linux/pull/25.patch