mm/migrate_device: fix spinlock leak in migrate_vma_insert_huge_pmd_page

When check_stable_address_space() fails after the PMD spinlock has
been acquired via pmd_lock(), the code jumps directly to the abort
label, bypassing the spin_unlock() call in unlock_abort. This causes
the PMD spinlock to be permanently held, leading to a deadlock.

Change the goto target from abort to unlock_abort to ensure the
spinlock is always released on this error path.

Link: https://lore.kernel.org/20260425133537.17463-1-nueralspacetech@gmail.com
Fixes: a30b48b ("mm/migrate_device: implement THP migration of zone device pages")
Signed-off-by: Sunny Patel <nueralspacetech@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: Balbir Singh <balbirs@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Nueralspace

mm/migrate_device.c

@@ -850,7 +850,7 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
 	ptl = pmd_lock(vma->vm_mm, pmdp);
 	csa_ret = check_stable_address_space(vma->vm_mm);
 	if (csa_ret)
-		goto abort;
+		goto unlock_abort;
 
 	/*
 	 * Check for userfaultfd but do not deliver the fault. Instead,