From: Kevin Easton > Sent: 22 November 2018 11:20 > > On Wed, Nov 21, 2018 at 12:14:44PM -0800, Daniel Colascione wrote: > > This change adds a per-pid-namespace 64-bit generation number, > > incremented on PID rollover, and exposes it via a new proc file > > /proc/pid_generation. By examining this file before and after /proc > > enumeration, user code can detect the potential reuse of a PID and > > restart the task enumeration process, repeating until it gets a > > coherent snapshot. > > I see downthread this patch has been withdrawn, but nonetheless I'm > still curious - does this actually solve the problem? > > It seems to me that a PID could be reused within a scan even if the > generation number remains the same at the beginning and end of a scan: Why not allocate a 48bit generation number to each 16bit pid? Then you have a 64bit 'extended-pid' that can be assumed to never be reused. Provided enough interfaces are enhanced to support 'extended-pid' values you'll never get reused values. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
