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AJvYcCU9ZfYd1uLmjDJzrKQ5rhY6f0/1SVsZqfE5VtVczYQr8JseGo/JmXZ/+YfqayDH6WwX1c87je6gTw==@kvack.org X-Gm-Message-State: AOJu0YzG/tzUw4HvhUsKwkSSAI+bgR19kqRLfdtB7PHIOl/ZILUDPXxl QrU2dX/GtDlS3RtqQPSp4s0Ue5DV2W4/lY0T2zMV5F9kJ4uT4Mt5m6Ab9xOTXqCkxdf5ca+a/Zt hMfzJqeOBJspFkfyzLzRoVC2QH60eX2k+TORXT4Li X-Gm-Gg: AY/fxX68sQ96nA2t90HvBEW/2+lc0Od48TMmN1c0CjoVbV/2QStdxXTcP0GrPaaIZd3 feDo4/14Hg6HX9gEf46RN8CUErMsx8hj9MQa2r24Hs0UOtufMI6YQsBsZTL2e8xGJLcA/oiyH/Y ShPZbNOLJJv7zHOs/OS116nhc3VnuyQcRuC74kDqmcRmRsOFbhpCtQMpdfBwC4qFIImZHxiKC7U EElxwOolEs7vU9EvAz66tCXt1sryV97n8QrqUR6k75bNb3a1ZiRdtLUxD9bd4jOGZOgYEqNgdcP eTsGlhRYp+4wVMlL1oZk3JWvQLf8DqItlPZW X-Google-Smtp-Source: AGHT+IEtTsutQpO25KKJJxkwWclrV1NkoOFyJBOS1res7lIatKk2McpUxH3uFSbvGt+LR+VAYJv6MCV9dzQjj1c4j+4= X-Received: by 2002:a05:6214:20c4:b0:87c:152c:7b25 with SMTP id 6a1803df08f44-8908417a83emr85986576d6.13.1767872399549; Thu, 08 Jan 2026 03:39:59 -0800 (PST) MIME-Version: 1.0 References: <20260105080230.13171-1-harry.yoo@oracle.com> <20260105080230.13171-2-harry.yoo@oracle.com> In-Reply-To: <20260105080230.13171-2-harry.yoo@oracle.com> From: Alexander Potapenko Date: Thu, 8 Jan 2026 12:39:22 +0100 X-Gm-Features: AQt7F2p4_VUyRgHz6qqEM5-JBZ5E2KV2nkrPg5vKNyZeCt2rwmq1SfsxSID667s Message-ID: Subject: Re: [PATCH V5 1/8] mm/slab: use unsigned long for orig_size to ensure proper metadata align To: Harry Yoo Cc: akpm@linux-foundation.org, vbabka@suse.cz, andreyknvl@gmail.com, cl@gentwo.org, dvyukov@google.com, hannes@cmpxchg.org, linux-mm@kvack.org, mhocko@kernel.org, muchun.song@linux.dev, rientjes@google.com, roman.gushchin@linux.dev, ryabinin.a.a@gmail.com, shakeel.butt@linux.dev, surenb@google.com, vincenzo.frascino@arm.com, yeoreum.yun@arm.com, tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, hao.li@linux.dev, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: BDEDE1C0003 X-Stat-Signature: iuu7bawz9oafcdng7ccb6o4aw7cbuksk X-HE-Tag: 1767872400-502725 X-HE-Meta: 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 qiiWzfzT udHzRopy6dtEKCc9a7eaVkXLmYDpRossAK7pfS66Bv1NoMIX8hVmnBoKz8FRj6g0q9quxJXZruoPoF/Zs8BaAFGMHKQUlYK/qC5rEPTISmMt3qy85uZU7WqMZ5ZcTNqrKe02dKUPvJeKeFgtuE4tQLcWZV3LsMEtFfNjzWYom41Z350AUNhlKTxXP4edX4zMnaxSLd467to6JoZsRJpAxjX0ZQK/7e6jvn0yFJPX1PJFY3VsAR+SGkQGisMfEX6b9Gs/KKOPJGMTQGqUYV5W8VB4g0Zp/2i2MXALZEzkltRKlHuv0XFPtOowettfko4/SNg/GHr92L/EYQMlAp/BDLBXguvRT55SYfsRGV8Vw+1b3BUyvSTph3ytg6GBOMUg0D8x9 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jan 5, 2026 at 9:02=E2=80=AFAM Harry Yoo wro= te: > > When both KASAN and SLAB_STORE_USER are enabled, accesses to > struct kasan_alloc_meta fields can be misaligned on 64-bit architectures. > This occurs because orig_size is currently defined as unsigned int, > which only guarantees 4-byte alignment. When struct kasan_alloc_meta is > placed after orig_size, it may end up at a 4-byte boundary rather than > the required 8-byte boundary on 64-bit systems. > > Note that 64-bit architectures without HAVE_EFFICIENT_UNALIGNED_ACCESS > are assumed to require 64-bit accesses to be 64-bit aligned. > See HAVE_64BIT_ALIGNED_ACCESS and commit adab66b71abf ("Revert: > "ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS"") for more details. > > Change orig_size from unsigned int to unsigned long to ensure proper > alignment for any subsequent metadata. This should not waste additional > memory because kmalloc objects are already aligned to at least > ARCH_KMALLOC_MINALIGN. > > Suggested-by: Andrey Ryabinin > Cc: stable@vger.kernel.org > Fixes: 6edf2576a6cc ("mm/slub: enable debugging memory wasting of kmalloc= ") > Signed-off-by: Harry Yoo > --- > mm/slub.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index ad71f01571f0..1c747435a6ab 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -857,7 +857,7 @@ static inline bool slab_update_freelist(struct kmem_c= ache *s, struct slab *slab, > * request size in the meta data area, for better debug and sanity check= . > */ > static inline void set_orig_size(struct kmem_cache *s, > - void *object, unsigned int orig_size) > + void *object, unsigned long orig_size) > { > void *p =3D kasan_reset_tag(object); > > @@ -867,10 +867,10 @@ static inline void set_orig_size(struct kmem_cache = *s, > p +=3D get_info_end(s); > p +=3D sizeof(struct track) * 2; > > - *(unsigned int *)p =3D orig_size; > + *(unsigned long *)p =3D orig_size; Instead of calculating the offset of the original size in several places, should we maybe introduce a function that returns a pointer to it?