The existing code tries to get the pmd for the temporary page table
by doing:
pgd = pgd_alloc(&init_mm);
pmd = pmd_offset(pgd, PHYS_OFFSET);
Since we have a two level page table, pmd_offset() is a no-op, so
this just has a casting effect from a pgd to a pmd - the address
argument is unused. So this can't work.
Normally, we'd do:
pgd = pgd_offset(&init_mm, PHYS_OFFSET);
...
pmd = pmd_offset(pgd, PHYS_OFFSET);
to get the pmd you want. However, pgd_offset() takes the mm_struct,
not the (unattached) pgd we just allocated. So, instead use:
pgd = pgd_alloc(&init_mm);
pmd = pmd_offset(pgd + pgd_index(PHYS_OFFSET), PHYS_OFFSET);
Reported-by: Antti P Miettinen <ananaza@iki.fi>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
058ddee562