Why not fix process ids?

Posted Sep 2, 2023 7:04 UTC (Sat) by Subsentient (guest, #142918)
In reply to: Why not fix process ids? by epa
Parent article: Race-free process creation in the GNU C Library

The obvious solution, the right solution, and I'm sure there's some irritating illegitimate reason that it won't happen.

Why not fix process ids?

Posted Sep 2, 2023 14:23 UTC (Sat) by corbet (editor, #1) [Link] (3 responses)

That can, indeed, be done now by messing with /proc/sys/kernel/pid_max. Making bigger process ID's the default will always risk breaking applications, though.

Why not fix process ids?

Posted Sep 2, 2023 16:04 UTC (Sat) by pebolle (guest, #35204) [Link]

Which has a hardcoded maximum of ~4,000,000 on 64 bits systems.

I could be misreading include/linux/threads.h, but since systemd on my (Fedora) system sets pid_max to that value out of the box I don't think I actually am.

Why not fix process ids?

Posted Sep 4, 2023 9:50 UTC (Mon) by mezcalero (subscriber, #45103) [Link] (1 responses)

systemd has been bumping this value to the max the kernel allows btw for a longer time. Not a single complaint reached us about that. The incompatibilities turned out to be mostly theoretic.

That said the kernel max is 22bit or so iirc, i.e. far from 32 or even 64bit...

Why not fix process ids?

Posted Sep 4, 2023 10:12 UTC (Mon) by pebolle (guest, #35204) [Link]

> the kernel max is 22bit or so iirc,

That's correct (and thanks for confirming my reading of include/linux/threads.h).