Date: Sat, 2 Jun 2018 22:40:52 +0000 From: John Howie <john@thehowies.com> To: Brennan Vincent <brennan@umanwizard.com> Cc: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: Re: Is it normal that a user can take down the whole system by using too much memory? Message-ID: <01EE7EEA-03AC-4D71-BA08-B0CEA97EE720@thehowies.com> In-Reply-To: <1527977770.2651378.1394286400.0806CC5C@webmail.messagingengine.com> References: <1527977770.2651378.1394286400.0806CC5C@webmail.messagingengine.com>
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Hi Brennan,
Do =91man -k limit=92 for details of means to restrict resource consumption=
. In particular, check out limits(1) and rctl(8).
Variations of this problem have been around forever. An oldie but goldie is=
:
main () { while (1) { fork (); } }
I cannot say why you are getting the results you see on your specific syste=
m. I would check limits to see where they are set, and tweak them.
Cheers,
John
Sent from my iPhone
> On Jun 2, 2018, at 15:20, Brennan Vincent <brennan@umanwizard.com> wrote:
>=20
> The attached program `eatmem.c` is a simple example to waste N gigs of me=
mory as quickly as possible.
>=20
> When I run something like `eatmem 32` (on a system with less than 32GB of=
RAM), about half the time everything works fine: the system quickly runs o=
ut of RAM and swap, the kernel kills `eatmem`, and everything recovers. How=
ever, the other half of the time, the system becomes completely unusable: m=
y ssh session is killed, important processes like `init` and `getty` are ki=
lled, and it's impossible to even log into the system (the local terminal i=
s unresponsive, and I can't ssh in because sshd is killed immediately whene=
ver it tries to run). The only way to recover is by rebooting.
>=20
> Is this expected behavior?
>=20
> My system details are as follows:
> FreeBSD 12 CURRENT x86_64 guest on VMWare Fusion.
> ram: 8 GB
> swap: 1 GB
> Host: macbook pro running macOS.
> <eatmem.c>
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