direct i/o problem with 2.4.21

[Larry Auton <lkml@winux.com>]

> Message-ID: <16107.26375.67524.817817@nv.winux.com>
> Date:   Sat, 14 Jun 2003 14:18:47 -0400
> To:     linux-kernel@vger.kernel.org
> From:   Larry Auton <lkml@winux.com>
> Subject: direct i/o problem with 2.4.20 and 2.4.21rc7
>
> I have an application that requires direct i/o to thousands of files.
> On 2.4.19 the open's would eventually fail (at around 7200 files).
> On 2.4.20 and 2.4.21rc7 the machine hangs.
> 
> Here's a sample program to do the deed:
> 
>     wget http://www.skarven.net/lda/crashme.c
>     cc -o crashme crashme.c     # compile it
>     ./crashme 4000              # OK
>     ./crashme 9999              # CRASH
> 
> It's a little obfuscated to eliminate the need for root privileges to
> mess with rlimit. It simply opens a bunch of files with O_DIRECT and,
> when enough files are open, the system will hang.
> 
> The system hangs when '/proc/slabinfo' reports that 'kiobuf' reaches 
> just over 7230 active objects. I don't believe that this problem is
> specific to any particular file system as the failure occurs when
> using both ext2 and reiserfs.
> 
> Larry Auton

The hang I reported on 2.4.21rc7 persists in the released version 2.4.21.

Larry