# Re: \[RFC PATCH v3 12/24\] x86/mm: Modify ptep\_set\_wrprotect and pmdp\_set\_wrprotect for \_PAGE\_DIRTY\_SW

- From: Dave Hansen \<dave.hansen@linux.intel.com\>
- Date: 2018-08-31 16:29:55 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2018/08/5368796
- Thread: https://ratatoskr.run/linux-doc/2018/08/5367691/t.md

```text
On 08/30/2018 07:38 AM, Yu-cheng Yu wrote:
> +	 * Some processors can start a write, but ending up seeing
> +	 * a read-only PTE by the time they get to the Dirty bit.
> +	 * In this case, they will set the Dirty bit, leaving a
> +	 * read-only, Dirty PTE which looks like a Shadow Stack PTE.
> +	 *
> +	 * However, this behavior has been improved and will not occur
> +	 * on processors supporting Shadow Stacks.  Without this
> +	 * guarantee, a transition to a non-present PTE and flush the
> +	 * TLB would be needed.

Did we publicly document this behavior anywhere?  I can't seem to find it.
```