swap_dup: Bad swap file entry 00480020

bogdan antonovici bantonovici at priority.mb.ca
Sat Jul 23 01:46:38 EST 2005

Hi Dan,

I checked the driver code. I found a pointer that was in my opinion
initialized too late and i corrected that but other than that i haven't
found anything.
I ran the driver alone, enabling the interrupts and the interrupt
routine doesn't cause any trouble.
I started my application and i haven't seen any sign of trouble.
But once i started also the snmpd after few interrupts i got the

__alloc_pages: 0-order allocation failed (gfp=0x1d2/0)
VM: killing process sectionmond

sectionmond being my application.
My read and write driver operation are requesting a page for a buffer
but they also release it. Should i declare the buffer pointer with
volatile attribute?
Do you know what may cause that message?

On Thu, 2005-07-21 at 12:59, Dan Malek wrote:
> On Jul 21, 2005, at 11:29 AM, bogdan antonovici wrote:
> > At the time of swap messages i was running a proprietary driver, my
> > application and few daemons.
> Looks like your driver may have written over some of the page
> tables in the kernel space.
> > I look on the net for some clues but it's quite confusing, i noticed
> > many emails on swap_dup/swap_free error messages but i couldn't figure
> > out what should i search for.
> Those messages are likely due to a bug with swapping to disk
> that has been in some 2.4 kernels, but I don't believe that is
> the case here, since you don't have a disk or swapping enabled.
> 	-- Dan

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