On Wed, May 15, 2019 at 5:11 PM Kirill Tkhai <[email protected]> wrote: > This patchset adds a new syscall, which makes possible > to clone a mapping from a process to another process. > The syscall supplements the functionality provided > by process_vm_writev() and process_vm_readv() syscalls, > and it may be useful in many situation. [...] > The proposed syscall aims to introduce an interface, which > supplements currently existing process_vm_writev() and > process_vm_readv(), and allows to solve the problem with > anonymous memory transfer. The above example may be rewritten as: > > void *buf; > > buf = mmap(NULL, n * PAGE_SIZE, PROT_READ|PROT_WRITE, > MAP_PRIVATE|MAP_ANONYMOUS, ...); > recv(sock, buf, n * PAGE_SIZE, 0); > > /* Sign of @pid is direction: "from @pid task to current" or vice > versa. */ > process_vm_mmap(-pid, buf, n * PAGE_SIZE, remote_addr, PVMMAP_FIXED); > munmap(buf, n * PAGE_SIZE);
In this specific example, an alternative would be to splice() from the socket into /proc/$pid/mem, or something like that, right? proc_mem_operations has no ->splice_read() at the moment, and it'd need that to be more efficient, but that could be built without creating new UAPI, right? But I guess maybe your workload is not that simple? What do you actually do with the received data between receiving it and shoving it over into the other process?
