linux-kernel - Re: [PATCH] aoe: adjust ref of head for compound page tails

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]

Date:	Wed, 7 Aug 2013 19:27:40 -0400
From:	Ed Cashin <ecashin@...aid.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] aoe: adjust ref of head for compound page tails

On Aug 7, 2013, at 5:26 PM, Andrew Morton wrote:

> On Wed, 7 Aug 2013 17:21:32 -0400 Ed Cashin <ecashin@...aid.com> wrote:
...
>> Sorry.  I tried to cover that but maybe should have separated it more clearly from the running text.
>> 
>> The patch changes the current behavior encountered with direct I/O and aoe:
>> 
>>  aoe can BUG when direct I/O used
>> 
>> ... to a new behavior:
>> 
>>  aoe does not BUG when direct I/O is used
>> 
>> And the user will never know that instead aoe is manipulating the _count of the head page, even though that's what's happening with this patch applied.
>> 
>> (The user-visible effects that motivated the older patch that added the BUG to aoe when page tails are used for block I/O was a VM_BUG_ON that occurred when the aoe driver manipulated the _count of a compound page tail.)
> 
> OK, I added "Fix a BUG which can trigger when direct-IO is used with
> AOE".  Which kernel versions are affected?


That BUG was added to the aoe driver in a commit that first appears in v3.7.  It persists until this patch adds the code that handles the situation that the BUG was intended to detect.

[ecashin@...ino linux]$ git describe --contains --match 'v*' 69cf2d85de773d998798e47e3335b85e5645d157
v3.7-rc1~110^2~22
[ecashin@...ino linux]$ 

-- 
  Ed Cashin
  ecashin@...aid.com


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/