Thank you for the very nice explanation on when you see the file mmap
info disappearing: this was a rather subtle bug..
It _should_ be fixed with this very simple patch:
In the file linux/mm/filemap.c, function filemap_sync(), there is a line
that says:
dir = pgd_offset(current->mm, address);
but it should be
dir = pgd_offset(vma->vm_mm, address);
(ie change "current->mm" into "vma->vm_mm"). Does that fix the problem
for you?
Linus