linux-kernel - Re: [RESEND PATCH v2] memory-hotplug: fix store_mem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.DEB.2.10.1608311652110.112811@chino.kir.corp.google.com>
Date:   Wed, 31 Aug 2016 17:03:25 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Reza Arbab <arbab@...ux.vnet.ibm.com>
cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Yaowei Bai <baiyaowei@...s.chinamobile.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Dan Williams <dan.j.williams@...el.com>,
        Xishi Qiu <qiuxishi@...wei.com>,
        David Vrabel <david.vrabel@...rix.com>,
        Chen Yucong <slaoub@...il.com>,
        Andrew Banman <abanman@....com>,
        Seth Jennings <sjenning@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v2] memory-hotplug: fix store_mem_state() return
 value

On Wed, 31 Aug 2016, Reza Arbab wrote:

> > The correct fix is for store_mem_state() to return -EINVAL when
> > device_online() returns non-zero.
> 
> Let me put it to you this way--which one of these sysfs operations is behaving
> correctly?
> 
> 	# cd /sys/devices/system/memory/memory0
> 	# cat online
> 	1
> 	# echo 1 > online; echo $?
> 	0
> 
> or
> 
> 	# cd /sys/devices/system/memory/memory0
> 	# cat state
> 	online
> 	# echo online > state; echo $?
> 	-bash: echo: write error: Invalid argument
> 	1
> 
> One of them should change to match the other.
> 

Nope, the return value of changing state from online to online was 
established almost 11 years ago in commit 3947be1969a9.  This was broken 
by commit fa2be40fe7c0 ("drivers: base: use standard device online/offline 
for state change") which was not intended to introduce a functional 
change, but it did (memory_block_change_state() would have returned 
EINVAL, device_online() does not).