Re: mmap'ed memory in core files ?

[Philippe De Muyter <phdm@macqel.be>]

Hi Hidehiro,
On Fri, Jul 04, 2008 at 02:50:25PM +0900, Hidehiro Kawai wrote:
[...]
> > I see the following ways to solve my problem :
> >     - do not tag the zone as VM_RESERVED in ieee1394::dma_region_mmap
> >     - tag the zone as VM_ALWAYSDUMP in ieee1394::dma_region_mmap
> >     - add a bit in coredump_filter to dump the VM_RESERVED zones.
> > 
> > As I don't know the real meaning of VM_RESERVED, I do not know which choice
> > is the best one for the official kernel tree, but locally I'll go for
> > adding VM_ALWAYSDUMP in ieee1394::dma_region_mmap.
> 
> I'm afraid I don't know real usages of VM_RESERVED and VM_IO, either.
> Allowing everyone to choose whether dump the dma region or not,
> perhaps we need to introduce a new VM flag (e.g. VM_DUMPABLE) and
> a coredump_filter bit which controls (VM_IO | VM_RESERVED) &&
> VM_DUMPABLE area, for example.
> 
> I think it is also OK to just add VM_ALWAYSDUMP flag to the dma
> region if the device driver knows the region is safely readable
> and small enough.

I have just submitted a patch doing that for ieee1394 dma regions:

http://marc.info/?l=linux-kernel&m=121510404729225&w=2

Thanks for your help

Philippe