Re: [RESEND PATCH v2] memory-hotplug: fix store_mem_state() return value

[Andrew Morton]

On Wed, 31 Aug 2016 10:44:01 -0500 Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx> wrote:

> Attempting to online memory which is already online will cause this:
> 
> 1. store_mem_state() called with buf="online"
> 2. device_online() returns 1 because device is already online
> 3. store_mem_state() returns 1
> 4. calling code interprets this as 1-byte buffer read
> 5. store_mem_state() called again with buf="nline"
> 6. store_mem_state() returns -EINVAL
> 
> Example:
> 
> $ cat /sys/devices/system/memory/memory0/state
> online
> $ echo online > /sys/devices/system/memory/memory0/state
> -bash: echo: write error: Invalid argument
> 
> Fix the return value of store_mem_state() so this doesn't happen.

So..  what *does* happen after the patch?  Is some sort of failure still
reported?  Or am I correct in believing that the operation will appear
to have succeeded?  If so, is that desirable?