linux-kernel - [PATCH 1/6] slab: Remove dead code in free_consistency

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Message-Id: <20250911-slub-slab-validation-v1-1-8b67eb3b3dc5@suse.cz>
Date: Thu, 11 Sep 2025 19:02:34 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: Harry Yoo <harry.yoo@...cle.com>, Christoph Lameter <cl@...two.org>, 
 David Rientjes <rientjes@...gle.com>, 
 Roman Gushchin <roman.gushchin@...ux.dev>, 
 Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org, 
 linux-kernel@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH 1/6] slab: Remove dead code in free_consistency_checks()

From: "Matthew Wilcox (Oracle)" <willy@...radead.org>

We already know that slab is a valid slab as that's checked by the
caller.  In the future, we won't be able to get to a slab pointer
from a non-slab page.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Harry Yoo <harry.yoo@...cle.com>
Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/slub.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 3062f56bf49882538ba5af407de9f69c451f2e29..56143bfd1ae319d384981c810a5ed84af00f4afa 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1684,10 +1684,7 @@ static inline int free_consistency_checks(struct kmem_cache *s,
 		return 0;
 
 	if (unlikely(s != slab->slab_cache)) {
-		if (!folio_test_slab(slab_folio(slab))) {
-			slab_err(s, slab, "Attempt to free object(0x%p) outside of slab",
-				 object);
-		} else if (!slab->slab_cache) {
+		if (!slab->slab_cache) {
 			slab_err(NULL, slab, "No slab cache for object 0x%p",
 				 object);
 		} else {

-- 
2.51.0