On Wed, Aug 23, 2017 at 04:48:40PM -0700, Dan Williams wrote: > We are running running short of vma->vm_flags. We can avoid needing a > new VM_* flag in some cases if the original @flags submitted to mmap(2) > is made available to the ->mmap() 'struct file_operations' > implementation. For example, the proposed addition of MAP_DIRECT can be > implemented without taking up a new vm_flags bit. Another motivation to > avoid vm_flags is that they appear in /proc/$pid/smaps, and we have seen > software that tries to dangerously (TOCTOU) read smaps to infer the > behavior of a virtual address range. > > This conversion was performed by the following semantic patch. There > were a few manual edits for oddities like proc_reg_mmap. > > Thanks to Julia for helping me with coccinelle iteration to cover cases > where the mmap routine is defined in a separate file from the 'struct > file_operations' instance that consumes it. How are we going to check that an instance actually supports any of those flags?
