Re: [RFC PATCH for 4.21 06/16] cpu_opv: Provide cpu_opv system call (v8)

From: Sergey Senozhatsky
Date: Tue Oct 16 2018 - 21:47:08 EST

Hi Mathieu,

On (10/16/18 15:17), Mathieu Desnoyers wrote:
> Therefore, only an internal kernel bug between vm_map_user_ram() and
> vm_unmap_user_ram() should trigger the BUG_ON(). No user input is passed
> to vm_unmap_user_ram().
> Now, let's look at vm_map_user_ram(). It calls alloc_vmap_area(), which returns
> a vmap_area. Then if vmap_page_range failed, vm_unmap_user_ram is called on the
> memory that has just been returned by vm_map_user_ram. Again, only an internal
> bug between map/unmap can trigger the BUG_ON() in vm_unmap_user_ram.

Thanks for spending time on this.
Just wanted someone to have extra look at syscall->BUG_ON().