Re: [PATCH v4 2/9] mm: add atomic VMA flags and set VM_MAYBE_GUARD as such

[David Hildenbrand (Red Hat)]

On 18.11.25 11:17, Lorenzo Stoakes wrote:
> This patch adds the ability to atomically set VMA flags with only the mmap
> read/VMA read lock held.
>
> As this could be hugely problematic for VMA flags in general given that
> all other accesses are non-atomic and serialised by the mmap/VMA locks, we
> implement this with a strict allow-list - that is, only designated flags
> are allowed to do this.
>
> We make VM_MAYBE_GUARD one of these flags.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> Reviewed-by: Pedro Falcato <pfalcato@xxxxxxx>
> Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---

IIUC all other flag modifications need a write lock, so this should just 
work.

Acked-by: David Hildenbrand (Red Hat) <david@xxxxxxxxxx>

--
Cheers

David