Re: [PATCH v2] mm/migrate: untag addresses when querying page nodes

[Catalin Marinas]

On Mon, Oct 26, 2026 at 07:53:29PM +0000, Hungyu Lin wrote:
> When move_pages() is used with nodes == NULL, do_pages_stat_array()
> passes each page address directly to vma_lookup(). A valid tagged address
> therefore fails the VMA lookup and gets -EFAULT in its status entry,
> instead of the node reported for the corresponding untagged address.
> 
> The tagged address ABI permits these pointers, and the migration path
> already removes their tags. Apply the target mm's untagging rules to
> the query path as well, while holding its mmap read lock.
> 
> Fixes: 057d3389108e ("mm: untag user pointers passed to memory syscalls")
> Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
> Closes: https://lore.kernel.org/r/20260721183257.706661F000E9@xxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Hungyu Lin <dennylin0707@xxxxxxxxx>
> Acked-by: Zi Yan <ziy@xxxxxxxxxx>
> Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>