[PATCH] mm/mincore: handle non-swap entries before !CONFIG_SWAP guard

[Usama Arif <usama.arif@linux.dev>]

mincore_swap() also fields migration/hwpoison entries (and shmem
swapin-error entries), which can exist on !CONFIG_SWAP builds when
CONFIG_MIGRATION or CONFIG_MEMORY_FAILURE is enabled.  The
!IS_ENABLED(CONFIG_SWAP) guard ran before the non-swap-entry early
return, so mincore_pte_range() can spuriously WARN and report these
pages nonresident on !CONFIG_SWAP kernels.

Move the guard below the non-swap-entry check so only true swap
entries trip the WARN, and migration/hwpoison entries take the
existing "uptodate / non-shmem" path.

Fixes: 1f2052755c15 ("mm/mincore: use a helper for checking the swap cache")
Signed-off-by: Usama Arif <usama.arif@linux.dev>
---
This was discovered when working on PMD swap entry series
(https://lore.kernel.org/all/20260602142537.198755-1-usama.arif@linux.dev/)
---
 mm/mincore.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/mincore.c b/mm/mincore.c
index e5d13eea9234..296f2e3922b5 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -64,11 +64,6 @@ static unsigned char mincore_swap(swp_entry_t entry, bool shmem)
 	struct folio *folio = NULL;
 	unsigned char present = 0;
 
-	if (!IS_ENABLED(CONFIG_SWAP)) {
-		WARN_ON(1);
-		return 0;
-	}
-
 	/*
 	 * Shmem mapping may contain swapin error entries, which are
 	 * absent. Page table may contain migration or hwpoison
@@ -77,6 +72,11 @@ static unsigned char mincore_swap(swp_entry_t entry, bool shmem)
 	if (!softleaf_is_swap(entry))
 		return !shmem;
 
+	if (!IS_ENABLED(CONFIG_SWAP)) {
+		WARN_ON(1);
+		return 0;
+	}
+
 	/*
 	 * Shmem mapping lookup is lockless, so we need to grab the swap
 	 * device. mincore page table walk locks the PTL, and the swap
-- 
2.52.0