What is the linuxdvb module?

It's a module written by me. It run's stable for the last six year's. Since the
latest kernel upgrade i got this BUG. This error is hard to reproduce, but it
seems to trigger when a highmem address (allocated in userspace) is passed to
vmalloc_to_page.

The problem is almost certainly in the driver's vmap_to_dma_addr() function. If
you can reporduce without the driver loaded, reopen the bug...

Hi wise guy, maybe you are touched by god, but if you can read and learn then
take some time and read the function vmalloc_to_page. And if this won't help
then take a look here http://bugzilla.kernel.org/show_bug.cgi?id=8928.
If you after that always think the macro BUG_ON() is a joke in highmem.c line
38, then you should change your job.

Good luck ....

To workaround the BUG inside the 'kmap_atomic_prot' function is to write your
own version of 'vmalloc_to_page'. The big point is to avoid the use of
'kmap_atomic_prot'. We don't need to reinvent the wheel. There is already a
similar function called 'lookup_address' in 'arch/i386/mm/pageattr.c'.
Unfortunately this function is not exported as SYMBOL. So we copy the code and
add two lines (see dvb_vmalloc_to_page) to have a working 'vmalloc_to_page'.


static pte_t *dvb_lookup_address(unsigned long address)
{
  pgd_t *pgd = pgd_offset_k(address);
  pud_t *pud;
  pmd_t *pmd;
  
  if (pgd_none(*pgd))
    return NULL;

  pud = pud_offset(pgd, address);
  if (pud_none(*pud))
    return NULL;

  pmd = pmd_offset(pud, address);
  if (pmd_none(*pmd))
    return NULL;
    
  if (pmd_large(*pmd))
    return (pte_t *)pmd;

  return pte_offset_kernel(pmd, address);
}

struct page* dvb_vmalloc_to_page(void * vmalloc_addr)
{
  struct page  *page = NULL;
  pte_t        *ppte, pte;

  ppte = dvb_lookup_address((unsigned long)vmalloc_addr);
  if (ppte != NULL)
  {
    pte = *ppte;
    if (pte_present(pte))
      page = pte_page(pte);
  }
  return page;
}

Fedora apologizes that these issues have not been resolved yet. We're
sorry it's taken so long for your bug to be properly triaged and acted
on. We appreciate the time you took to report this issue and want to
make sure no important bugs slip through the cracks.

If you're currently running a version of Fedora Core between 1 and 6,
please note that Fedora no longer maintains these releases. We strongly
encourage you to upgrade to a current Fedora release. In order to
refocus our efforts as a project we are flagging all of the open bugs
for releases which are no longer maintained and closing them.
http://fedoraproject.org/wiki/LifeCycle/EOL

If this bug is still open against Fedora Core 1 through 6, thirty days
from now, it will be closed 'WONTFIX'. If you can reporduce this bug in
the latest Fedora version, please change to the respective version. If
you are unable to do this, please add a comment to this bug requesting
the change.

Thanks for your help, and we apologize again that we haven't handled
these issues to this point.

The process we are following is outlined here:
http://fedoraproject.org/wiki/BugZappers/F9CleanUp

We will be following the process here:
http://fedoraproject.org/wiki/BugZappers/HouseKeeping to ensure this
doesn't happen again.

And if you'd like to join the bug triage team to help make things
better, check out http://fedoraproject.org/wiki/BugZappers

This bug is open for a Fedora version that is no longer maintained and
will not be fixed by Fedora. Therefore we are closing this bug.

If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen thus bug against that version.

Thank you for reporting this bug and we are sorry it could not be fixed.