linux-kernel - Re: aio: compat

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Message-ID: <4B957AF3.6040801@msgid.tls.msk.ru>
Date:	Tue, 09 Mar 2010 01:32:19 +0300
From:	Michael Tokarev <mjt@....msk.ru>
To:	Jeff Moyer <jmoyer@...hat.com>
CC:	linux-aio@...ck.org, Linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: aio: compat_ioctl issue?

Jeff Moyer wrote:
[]
>>>> I just come across a situation (next in a long row :)
>>>> when on x86, 32bit userspace does not work with 64bit
>>>> kernel.  This time this is about aio requests.
> [snip]

> Well, I'm not experiencing such problems.  I can run a 32bit aio
> application on a 64bit kernel just fine with 2.6.31, 2.6.32 and
> 2.6.34-rc1.

Interesting.  I mentioned that I _think_ I used Oracle 32bit with
AIO on 64bit kernel, but I'm not sure.

> Could you maybe print out the values that are passed to io_getevents?

They were in my first email, here it goes again:

io_submit: lio_opcode=7 reqprio=0 iov=0x9cd7018{0xf5599000,4096}, niov=1, offset=0
io_getevents: expected 4096 got -22 (EINVAL)

This is what gets passed to libaio -- strace here
does not decode the arguments unfortunately.

The file in question is raw partition open with O_DIRECT,
if that makes any difference.

64bit binary uses very similar arguments except that
addresses are different.

My *guess* is that it handles read/write correctly but
does not properly handle preadv/pwritev (opcode=7 is
IO_CMD_PREADV as far as I can see).  That'll explain
my "testcase" with Oracle which does not use preadv.

Thanks!

/mjt
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