On 22.05.2019 18:22, Kirill A. Shutemov wrote:

On Mon, May 20, 2019 at 05:00:01PM +0300, Kirill Tkhai wrote:

quoted

This patchset adds a new syscall, which makes possible
to clone a VMA from a process to current process.
The syscall supplements the functionality provided
by process_vm_writev() and process_vm_readv() syscalls,
and it may be useful in many situation.

Kirill, could you explain how the change affects rmap and how it is safe.

My concern is that the patchset allows to map the same page multiple times
within one process or even map page allocated by child to the parrent.

Speaking honestly, we already support this model, since ZERO_PAGE() may
be mapped multiply times in any number of mappings.

Kirill