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

On Tue, 13 Feb 2024 14:38:16 -0800
Kees Cook [off-list ref] wrote:

quoted

quoted

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.

You can create your own file system, but I would suggest using kernfs for it ;-)

If you look in /sys/kernel/ you'll see a bunch of kernel file systems already there:

 ~# mount |grep kernel
 securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
 debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)
 tracefs on /sys/kernel/tracing type tracefs (rw,nosuid,nodev,noexec,relatime)
 configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)

-- Steve