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    SubjectRe: [RFC][v7][PATCH 0/9] Implement clone2() system call

    Sukadev Bhattiprolu wrote:
    > To support application checkpoint/restart, a task must have the same pid it
    > had when it was checkpointed. When containers are nested, the tasks within
    > the containers exist in multiple pid namespaces and hence have multiple pids
    > to specify during restart.
    > This patchset implements a new system call, clone2() that lets a process
    > specify the pids of the child process.
    > Patches 1 through 6 are helper patches, needed for choosing a pid for the
    > child process.
    > Patch 8 defines a prototype of the new system call. Patch 9 adds some
    > documentation on the new system call, some/all of which will eventually
    > go into a man page.


    > Based on these requirements and constraints, we explored a couple of system
    > call interfaces (in earlier versions of this patchset) and currently define
    > the system call as:
    > struct clone_struct {
    > u64 flags;
    > u64 child_stack;
    > u32 nr_pids;
    > u32 parent_tid;
    > u32 child_tid;

    So @parent_tid and @child_tid are pointers to userspace memory and
    require 'u64' (and it won't hurt to make @reserved1 a 'u64' as well).

    > u32 reserved1;
    > u64 reserved2;
    > };

    Also, for forward/backward compatibility, explicitly state in the
    documentation, and enforce in the kernel, that flags which are not
    defined must not be set, and that reserved{1,2} must remain 0.

    > sys_clone2(struct clone_struct __user *cs, pid_t __user *pids)
    > Signed-off-by: Sukadev Bhattiprolu <>

    Otherwise, looks great.


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      Last update: 2009-09-24 19:47    [W:0.031 / U:3.064 seconds]
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