Re: [PATCH] kernel: sysctl: make drop_caches write-only

[Andrew Morton]

On Fri, 1 Nov 2019 12:29:20 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> > Either change is an upgrade from the current situation, at least. I prefer 
> > towards whatever makes the API the least confusing, which appears to be 
> > Johannes' original change, but I'd support a patch which always set it to 
> > 0 instead if it was deemed safer.
> 
> On the other hand..  As I mentioned earlier, if someone's code is
> failing because of the permissions change, they can chmod
> /proc/sys/vm/drop_caches at boot time and be happy.  They have no such
> workaround if their software misbehaves due to a read always returning
> "0".

I lied.  I can chmod things in /proc but I can't chmod things in
/proc/sys/vm.  Huh, why did we do that?