Gerd Hoffmann wrote:
Yes, except that it should actually work ;)
It doesn't for me (Fedora 8 again). Grab xenner 0.9 (just uploaded),
edit blkbackd.c and flip the BATCH_MAPS from 0 to 1, compile, run, see
it not work.
Which version of the Xen tools are you using? There was a bug in the
Hi Gerd,
Gerd Hoffmann wrote:
Want reproduce? Here we go:
* grab xenner 0.8 from http://dl.bytesex.org/releases/xenner/
* grab a xenified dom0 kernel without blktap driver (either not
compiled or module not loaded).
* start xend
* start blkbackd from xenner package (you probably
Gerd,
Can you try the attached patch against linux-2.6.18-xen.hg?
I think the problem was that the gntdev VMA is not marked as being
VM_PFNMAP, therefore it tries to get a struct page_struct for each
granted page when it is unmapped (and maybe sometimes succeeds
(incorrectly), which could be
present) page_struct associated with the
granted PFN.
Signed-off-by: Derek Murray [EMAIL PROTECTED]
diff -r b2768401db94 -r af26b3dd2382 drivers/xen/gntdev/gntdev.c
--- a/drivers/xen/gntdev/gntdev.c Mon Dec 03 08:50:12 2007 +
+++ b/drivers/xen/gntdev/gntdev.c Wed Dec 05 13:13:02 2007 +
ID df7d0555ec3847bd5915063d8ee79123d6ebc67a
# Parent ba918cb2cf7520604dee724dd80dad5ce4bee8a1
Changed vm_normal_page to return NULL when presented with a VMA marked
as being VM_FOREIGN.
Signed-off-by: Derek Murray [EMAIL PROTECTED]
diff -r ba918cb2cf75 -r df7d0555ec38 mm/memory.c
--- a/mm/memory.c
Jeremy Fitzhardinge wrote:
Could we use one of the software-defined bits in the PTE to indicate
that this is a foreign/granted PTE, and have set_pte_at behave
differently if you pass it a pte with this bit set?
Actually, as Gerd pointed out in his answer to his own question, the use
of
Keir Fraser wrote:
Actually I'm not so sure now. Presumably you add VM_PFNMAP to make
vm_normal_page() return NULL? But actually I would expect pte_pfn() to
return max_mapnr because the mapped page is not a local page. And that
should cause vm_normal_page() to return NULL always, regardless of
Keir Fraser wrote:
Need to bite the bullet and fix this properly by setting a software flag in
ptes that are not subject to reference counting.
Could we get away with testing the VM_FOREIGN flag in vm_normal_page()?
Although I get the impression that this wouldn't be easily justified if
Stephen C. Tweedie wrote:
So... the interface (a) cannot be used on the Linux VM without at least
one invasive VM modification, due to the requirement of ptes being
explicitly unmapped via hypercall;
Also there is the use of VM_FOREIGN
Gerd Hoffmann wrote:
On this point I completely agree with you! If anyone has any less
radical suggestions, then I'd be delighted to refactor the gntdev code
to use them. However, I'm not currently aware of any alternative that
maintains robustness to process crashes.
Oh, for me it isn't
Gerd Hoffmann wrote:
Derek Murray wrote:
I take the blame for that one. I added the hook because, if a process
were to die whilst holding one or more grants, there were no hooks that
would make it possible to carry out the grant-unmap. All existing hooks
on either the device or the VMA were
) behaviour would be a retrograde
step IMHO.
Cheers,
Derek Murray.
Gerd Hoffmann wrote:
Stephen C. Tweedie wrote:
Hi all,
driver domains
Looked at the gntdev (grant table mappings for user space) driver,
noticed that one is not self-contained. It needs a hook for page unmapping:
http
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