Re: [RFC] Warn the user when they could overflow mapcount

From: Matthew Wilcox
Date: Thu Feb 08 2018 - 13:56:55 EST


On Thu, Feb 08, 2018 at 01:05:33PM -0500, Daniel Micay wrote:
> The standard map_max_count / pid_max are very low and there are many
> situations where either or both need to be raised.

[snip good reasons]

> I do think the default value in the documentation should be fixed but
> if there's a clear problem with raising these it really needs to be
> fixed. Google either of the sysctl names and look at all the people
> running into issues and needing to raise them. It's only going to
> become more common to raise these with people trying to use lots of
> fine-grained sandboxing. Process-per-request is back in style.

So we should make the count saturate instead, then? That's going to
be interesting.