Re: [PATCH] zram: restrict add/remove attributes to root only

[Sergey Senozhatsky]

On (12/04/16 11:28), Greg KH wrote:
> On Sun, Dec 04, 2016 at 11:35:15AM +0900, Sergey Senozhatsky wrote:
[..]

> Why can't a normal user read the attribute?  Does a read actually modify
> something?

yes, it does.

reading from a hot_add file creates a new zram device and returns a new
device's device_id. not initialized device (so it does not eat the memory
for handle table, etc.), but with its own set of sysfs attrs, etc. which
consumes memory after all. so a 'normal' user, doing a simple read from a
hot_add file in a loop just for fun, can create a lot of devices and,
quite likely, cause some troubles (as reported by Steven Allen).

	-ss