Re: [PATCH RFC] mm: userfaultfd: correct dirty flags set for both present and swap pte

[Peter Xu]

On Thu, May 08, 2025 at 09:07:35PM +1200, Barry Song wrote:
> From: Barry Song <v-songbaohua@xxxxxxxx>
> 
> As David pointed out, what truly matters for mremap and userfaultfd
> move operations is the soft dirty bit. The current comment and
> implementation—which always sets the dirty bit for present PTEs
> and fails to set the soft dirty bit for swap PTEs—are incorrect.
> This patch updates the behavior to correctly set the soft dirty bit
> for both present and swap PTEs in accordance with mremap.
> 
> Reported-by: David Hildenbrand <david@xxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-mm/02f14ee1-923f-47e3-a994-4950afb9afcc@xxxxxxxxxx/
> Cc: Peter Xu <peterx@xxxxxxxxxx>
> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>

Acked-by: Peter Xu <peterx@xxxxxxxxxx>

-- 
Peter Xu