Re: mmap denywrite mess (Was: [GIT PULL] overlayfs fixes for 5.14-rc6)

From: David Hildenbrand
Date: Thu Aug 12 2021 - 03:13:01 EST

On 11.08.21 18:20, Linus Torvalds wrote:
On Wed, Aug 11, 2021 at 4:45 AM David Hildenbrand <david@xxxxxxxxxx> wrote:

I proposed a while ago to get rid of VM_DENYWRITE completely:

I haven't looked how much it still applies to current upstream, but
maybe that might help cleaning up that code.

I like it.

I agree that we could - and probably should - just do it this way.

We don't expose MAP_DENYWRITE to user space any more - and the old
legacy library loading code certainly isn't worth it - and so
effectively the only way to set it is with execve().

And yes, it gets rid of all the silly games with the per-mapping flags.

I'll rebase, retest and resend, putting you on cc. Then we can discuss if/how/when we might want to go that path.


David / dhildenb