fs/proc/task_mmu: do not warn on seeing non-migration pmd entry

Patch series "mm/hmm: A fix and a selftest", v3.

Patch 1 fixes a stale warning present from the time when only migration
softleaf entries were supported at the PMD level.

Patch 2 adds some code into hmm-tests.c which exercises the pagemap path
for PMD device-private entries.

This patch (of 2):

pagemap_pmd_range_thp() warns if a non-present PMD is not a migration
entry.  This became false once device-private entries at the PMD level
were added.

Therefore, remove the stale migration-only assertion.

Link: https://lore.kernel.org/20260604055308.1947679-1-dev.jain@arm.com
Link: https://lore.kernel.org/20260604055308.1947679-2-dev.jain@arm.com
Fixes: a30b48bf1b24 ("mm/migrate_device: implement THP migration of zone device pages")
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Tested-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Oscar Salvador (SUSE) <osalvador@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 06fb94a965ff91674e331186d4a58ec8473d1501..d32408f7cd5ed25b41994afaa787dfa912eaaa83 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -2129,7 +2129,6 @@ static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigned long addr,
                        flags |= PM_SOFT_DIRTY;
                if (pmd_swp_uffd_wp(pmd))
                        flags |= PM_UFFD_WP;
-               VM_WARN_ON_ONCE(!pmd_is_migration_entry(pmd));
                page = softleaf_to_page(entry);
        }