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    SubjectRe: [PATCH v5 0/4] vm: add a syscall to map a process memory into a pipe
    On Wed, Feb 28, 2018 at 10:12:55AM +0300, Pavel Emelyanov wrote:
    > On 02/27/2018 05:18 AM, Dmitry V. Levin wrote:
    > > On Mon, Feb 26, 2018 at 12:02:25PM +0300, Pavel Emelyanov wrote:
    > >> On 02/21/2018 03:44 AM, Andrew Morton wrote:
    > >>> On Tue, 9 Jan 2018 08:30:49 +0200 Mike Rapoport <rppt@linux.vnet.ibm.com> wrote:
    > >>>
    > >>>> This patches introduces new process_vmsplice system call that combines
    > >>>> functionality of process_vm_read and vmsplice.
    > >>>
    > >>> All seems fairly strightforward. The big question is: do we know that
    > >>> people will actually use this, and get sufficient value from it to
    > >>> justify its addition?
    > >>
    > >> Yes, that's what bothers us a lot too :) I've tried to start with finding out if anyone
    > >> used the sys_read/write_process_vm() calls, but failed :( Does anybody know how popular
    > >> these syscalls are?
    > >
    > > Well, process_vm_readv itself is quite popular, it's used by debuggers nowadays,
    > > see e.g.
    > > $ strace -qq -esignal=none -eprocess_vm_readv strace -qq -o/dev/null cat /dev/null
    >
    > I see. Well, yes, this use-case will not benefit much from remote splice. How about more
    > interactive debug by, say, gdb? It may attach, then splice all the memory, then analyze
    > the victim code/data w/o copying it to its address space?

    Hmm, in this case, you probably will want to be able to map pipe pages
    into memory.

    >
    > -- Pavel

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