Re: [PATCH RFC 0/4] fs: port files to rcuref_long_t

[Al Viro <viro@zeniv.linux.org.uk>]

On Sat, Oct 05, 2024 at 03:43:16PM -0700, Linus Torvalds wrote:

> Come on - the only possible reason for two billion files is a bad
> user. Do we care what error return an attacker gets? No. We're not
> talking about breaking existing programs.

Umm...  It can be a bad failure mode of a buggy program, really
unpleasant to debug if the pile of references kept growing on stdin
of that sucker, which just happens to be controlling tty of your
login session; fork(2) starting to fail for everything that has it
opened is not fun.

That's really nit-picking though, since

> So I don't think that's actually the important thing here. If we keep
> it a 'long', I won't lose any sleep over it.

... exactly.

> But using the rcuref code doesn't work (regardless of whether 32-bit
> or 'long' ref), because of the memory ordering issues.

*nod*