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

["Zi Yan" <ziy@nvidia.com>]

On Sun Oct 25, 2026 at 6:32 PM EDT, 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@kernel.org>
> Link: https://lore.kernel.org/r/20260721183257.706661F000E9@smtp.kernel.org

It should be "Closes:"

> Cc: stable@vger.kernel.org
> Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>
> ---
>  mm/migrate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 7e3a81f06974..994c78782a54 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2461,7 +2461,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
>  	mmap_read_lock(mm);
>  
>  	for (i = 0; i < nr_pages; i++) {
> -		unsigned long addr = (unsigned long)(*pages);
> +		unsigned long addr = (unsigned long)untagged_addr_remote(mm, *pages);
>  		struct vm_area_struct *vma;
>  		struct folio_walk fw;
>  		struct folio *folio;

LGTM. add_folio_for_migration() does the same thing for user pointer p.

Acked-by: Zi Yan <ziy@nvidia.com>


-- 
Best Regards,
Yan, Zi