Re: vm_ops.page_mkwrite() fails with vmalloc on 2.6.23

["Jaya Kumar" <jayakumar.lkml@gmail.com>]

On 10/30/07, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> So page->index does what you want it to, identify which part of the
> framebuffer this particular page belongs to.

Ok. I'm attempting to walk the code sequence. Here's what I think:

- driver loads
- driver vmalloc()s its fb
- this creates the necessary pte entries
then...
- app mmap(/dev/fb0)
- vma is created
- defio mmap adds this vma to private list (equivalent of
address_space or anon_vma)
- app touches base + pixel(128,128) = base + 16k
- page fault
- defio nopage gets called
- defio nopage does vmalloc_to_page(base+16k)
- that finds the correct struct page corresponding to that vaddr.
page->index has not been set by anyone so far, right?
* ah... i see, you are suggesting that this is where I could set the
index since i know the offset i want it to represent. right?
- defio mkwrite get called. defio adds page to its list. schedules delayed work
- app keeps writing the page
- delayed work occurs
- foreach vma { foreach page { page_mkclean_one(page, vma) }
- cycle repeats...

Thanks,
jaya

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