From: Usama Arif <usama.arif@linux.dev>
Date: Tue, 2 Jun 2026 17:22:47 +0000 (-0700)
Subject: mm/mincore: handle non-swap entries before !CONFIG_SWAP guard
X-Git-Tag: v7.1~25^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0c25b8734367574e21aeb8468c2e522713134da7;p=thirdparty%2Flinux.git

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

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.

Link: https://lore.kernel.org/20260602172247.279421-1-usama.arif@linux.dev
Fixes: 1f2052755c15 ("mm/mincore: use a helper for checking the swap cache")
Signed-off-by: Usama Arif <usama.arif@linux.dev>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mincore.c b/mm/mincore.c
index e5d13eea92347..296f2e3922b5f 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