linux-kernel - Re: SCSI GENERIC command queueing for block storage is unstable.

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: <4B9EC36F.8010404@gmail.com>
Date:	Mon, 15 Mar 2010 17:31:59 -0600
From:	Robert Hancock <hancockrwd@...il.com>
To:	Mike Hayward <hayward@...p.net>
CC:	linux-kernel@...r.kernel.org, mvds.00@...il.com
Subject: Re: SCSI GENERIC command queueing for block storage is unstable.

On 03/15/2010 12:25 PM, Mike Hayward wrote:
> After discovering that O_NONBLOCK reads and writes were actually
> blocking calls, I attempted to use the SCSI generic driver for
> nonblocking io.  The good news is that it is nonblocking; the bad news
> is that it is not dependable in any of the systems I have tested with.
>
> Does anyone know if these defects have been fixed in later kernels?
>
> 1. When queueing, write can occassionally return errno 12 (ENOMEM, Cannot
>     allocate memory).  This is documented in the SCSI GENERIC HOWTO,
>     however only for indirect io and it says extremely rare.  I can cause
>     it easily within a few hours and it can return even for direct io when
>     no io's are queued and 80% of the ram is free or in buffer cache.  The
>     fd polls as available for writing, but retrying never clears the error
>     and the fd is no longer usable.  This is a complete show stopper.
>
>     Linux 2.6.22.1-32.fc6 #1 SMP Wed Aug 1 14:30:16 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux

First off, have you tested any of these problems against a newer kernel?
--
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/