Re: memory allocation error messages in system log

[Willy Tarreau <willy@w.ods.org>]

Hi Marcelo,

there are a lot of sprintf() in gdth_get_info(). There are a few overflow
checks, but they're being done *after* the problem happens, so it may
be possible that people experiencing problems get some data overwritten
which prevents something else from been released later.

Moreover, when some of those checks decide that the buffer is full, they
jump to stop_output without calling gdth_ioctl_free(). So it may also be
possible that this user who regularly reads /proc has his output truncated
and some memory never freed.

Regards,
Willy

On Fri, Sep 17, 2004 at 10:04:59PM -0300, Marcelo Tosatti wrote:
> 
> Achim,
> 
> This is not the first person I see complaining about 
> exact same bug (memory allocation failure while reading
> /proc/scsi/gdt/xxx
> 
> Do you have a card around so we can test?
> 
> Thanks
> 
> On Thu, Sep 16, 2004 at 06:14:08PM -0300, Marcelo Tosatti wrote:
> > On Thu, Sep 16, 2004 at 02:48:40PM +0200, Ingo Freund wrote:
> > > Hello,
> > > 
> > > I hope you guys can help, I cannot use any kernel 2.4 >23 without
> > > the here described problem.
> > > 
> > > [1.] One line summary of the problem:
> > > strange error messages concerning memory allocation
> > > 
> > > searching teh web for solutions to my problem I have already found
> > > a thread in a mailing list but no solution was mentioned, also the
> > > guys who talked about the error didn't answer to my direct mail.
> > > 
> > > [2.] Full description of the problem/report:
> > > The machine is a database server without any other service except sshd
> > > running. I do some tests on the ICP-Vortex GDT controller every 2 minutes.
> > > by using
> > > # cat /proc/scsi/gdt/2
> > > but the output of cat stops without beeing completed.
> > > 
> > > This is what I see in the syslog file every time when I use the cat
> > > command (the messages beginn after 3 days uptime):
> > > --> /var/log/messages
> > > kernel: __alloc_pages: 0-order allocation failed (gfp=0x21/0)
> > 
> > Ingo,
> > 
> > I've seen another report like this one - I'm convinced there
> > is something odd with the gdth proc handling code.
> > 
> > Can you "echo 1 > /proc/sys/vm/vm_gfp_debug" and 
> > rerun the "cat /proc/scsi/gdt/2" please?
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