Re: limits.conf/stacksize doesn't seem to work?

On Fri, Jul 15, 2022 at 05:26:09PM -0500, Larry Rosenman wrote:
> On 07/15/2022 5:24 pm, Mark Johnston wrote:
> > On Fri, Jul 15, 2022 at 05:21:27PM -0500, Larry Rosenman wrote:
> >> On 07/15/2022 5:18 pm, Mark Johnston wrote:
> >> > On Fri, Jul 15, 2022 at 05:04:18PM -0500, Larry Rosenman wrote:
> >> >> I'm using the following kernel config:
> >> >> [...]
> >> >> and the following login.conf:
> >> >> [...]
> >> >> bacula_dir:\
> >> >> 	:stacksize-max=68719476736:\
> >> >> 	:stacksize-cur=68719476736:\
> >> >> 	:tc=daemon:
> >> >> [...]
> >> >> I've updated my (ler) password entry to reference bacula_dir:
> >> >> ler:<elided>:1001:1001:bacula_dir:0:0:Larry
> >> >> Rosenman:/home/ler:/usr/local/bin/zsh
> >> >>
> >> >>
> >> >> when I ssh in, the stacklimit is still:
> >> >> ❯ ulimit -H -s
> >> >> 2097152
> >> >
> >> > What is the value of the kern.maxssiz sysctl on this system?
> >> >
> >> >> ler in 🌐 borg in sys/amd64/conf🔒 on  ler/freebsd-main-changes:main on
> >> >> ☁️  (us-east-1)
> >> >> ❯ ulimit -S -s
> >> >> 2097152
> >> >>
> >> >> ler in 🌐 borg in sys/amd64/conf🔒 on  ler/freebsd-main-changes:main on
> >> >> ☁️  (us-east-1)
> >> >> ❯
> >> >>
> >> >> Where does this number come from?  What am I missing here?
> >> >
> >> > The stack limit cannot be set to an arbitrarily large number.  It will
> >> > silently be clamped to maxssiz.
> >> 
> >> ❯ sysctl kern.maxssiz
> >> kern.maxssiz: 2147483648
> > 
> > Then what you're seeing is expected.  The kernel is clamping the stack
> > segment limit to 2GB.
> 
> I assume this is the default for MAXSSIZ?  and if I change that in the 
> kernel config, it will
> allow bigger?  Where is this default defined?

The default value is platform dependent.  On amd64 it's 512MB, so I'm
not sure where your value is coming from.  It's defined in a header.
You can set it in the kernel configuration, or as a tunable or sysctl.