inconsistence in mprotect_fixup mlock_fixup madvise_update_vma

[Jeff Xu <jeffxu@xxxxxxxxxxxx>]

Hello,

There seems to be inconsistency in different VMA fixup
implementations, for example:
mlock_fixup will skip VMA that is hugettlb, etc, but those checks do
not exist in mprotect_fixup and madvise_update_vma. Wouldn't this be a
problem? the merge/split skipped by mlock_fixup, might get acted on in
the madvice/mprotect case.

mlock_fixup currently check for
if (newflags == oldflags || (oldflags & VM_SPECIAL) ||
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
vma_is_dax(vma) || vma_is_secretmem(vma))

Should there be a common function to handle VMA merge/split ?

Best
-Jeff