On Fri 2018-11-23 11:14:17, David Laight wrote: > 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 I see downthread this patch has been withdrawn, but nonetheless I'm 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. For the record, I really like this proposal. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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