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

From: David Hildenbrand (Arm)

Date: Fri Feb 06 2026 - 04:42:40 EST


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@xxxxxxxxxx>
Reviewed-by: Muchun Song <muchun.song@xxxxxxxxx>
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Reviewed-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

--
Cheers,

David