Re: [PATCHv6 13/17] hugetlb: Remove VMEMMAP_SYNCHRONIZE_RCU

David Hildenbrand (Arm)
2026-02-06T09:42:32Z

On 2/2/26 16:56, Kiryl Shutsemau wrote:
> The VMEMMAP_SYNCHRONIZE_RCU flag triggered synchronize_rcu() calls to
> prevent a race between HVO remapping and page_ref_add_unless(). The
> race could occur when a speculative PFN walker tried to modify the
> refcount on a struct page that was in the process of being remapped
> to a fake head.
>
> With fake heads eliminated, page_ref_add_unless() no longer needs RCU
> protection.
>
> Remove the flag and synchronize_rcu() calls.
>
> Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
> Reviewed-by: Muchun Song <muchun.song@linux.dev>
> ---

Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>

--
Cheers,

David