Re: [PATCH v3 13/35] lib: add allocation tagging support for memory allocation profiling

Kees Cook
2024-02-13T22:38:18Z

On Tue, Feb 13, 2024 at 02:35:29PM -0800, Suren Baghdasaryan wrote:
> On Tue, Feb 13, 2024 at 2:29 PM Darrick J. Wong <djwong@kernel.org> wrote:
> >
> > On Mon, Feb 12, 2024 at 05:01:19PM -0800, Suren Baghdasaryan wrote:
> > > On Mon, Feb 12, 2024 at 2:40 PM Kees Cook <keescook@chromium.org> wrote:
> > > >
> > > > On Mon, Feb 12, 2024 at 01:38:59PM -0800, Suren Baghdasaryan wrote:
> > > > > Introduce CONFIG_MEM_ALLOC_PROFILING which provides definitions to easily
> > > > > instrument memory allocators. It registers an "alloc_tags" codetag type
> > > > > with /proc/allocinfo interface to output allocation tag information when
> > > >
> > > > Please don't add anything new to the top-level /proc directory. This
> > > > should likely live in /sys.
> > >
> > > Ack. I'll find a more appropriate place for it then.
> > > It just seemed like such generic information which would belong next
> > > to meminfo/zoneinfo and such...
> >
> > Save yourself a cycle of "rework the whole fs interface only to have
> > someone else tell you no" and put it in debugfs, not sysfs. Wrangling
> > with debugfs is easier than all the macro-happy sysfs stuff; you don't
> > have to integrate with the "device" model; and there is no 'one value
> > per file' rule.
>
> Thanks for the input. This file used to be in debugfs but reviewers
> felt it belonged in /proc if it's to be used in production
> environments. Some distros (like Android) disable debugfs in
> production.

FWIW, I agree debugfs is not right. If others feel it's right in /proc,
I certainly won't NAK -- it's just been that we've traditionally been
trying to avoid continuing to pollute the top-level /proc and instead
associate new things with something in /sys.

--
Kees Cook