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Wed, 29 Oct 2025 11:19:37 -0700 (PDT) Message-ID: Date: Wed, 29 Oct 2025 19:19:29 +0100 Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH V3 7/7] mm/slab: place slabobj_ext metadata in unused space within s->size To: Harry Yoo , akpm@linux-foundation.org, vbabka@suse.cz Cc: andreyknvl@gmail.com, cl@linux.com, dvyukov@google.com, glider@google.com, hannes@cmpxchg.org, linux-mm@kvack.org, mhocko@kernel.org, muchun.song@linux.dev, rientjes@google.com, roman.gushchin@linux.dev, 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 References: <20251027122847.320924-1-harry.yoo@oracle.com> <20251027122847.320924-8-harry.yoo@oracle.com> Content-Language: en-US From: Andrey Ryabinin In-Reply-To: <20251027122847.320924-8-harry.yoo@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/27/25 1:28 PM, Harry Yoo wrote: > slab->obj_exts |= MEMCG_DATA_OBJEXTS; > slab_set_stride(slab, sizeof(struct slabobj_ext)); > + } else if (obj_exts_in_object(s)) { > + unsigned int offset = obj_exts_offset_in_object(s); > + > + slab->obj_exts = (unsigned long)slab_address(slab); > + slab->obj_exts += s->red_left_pad; > + slab->obj_exts += obj_exts_offset_in_object(s); > + if (IS_ENABLED(CONFIG_MEMCG)) > + slab->obj_exts |= MEMCG_DATA_OBJEXTS; > + slab_set_stride(slab, s->size); > + > + for_each_object(addr, s, slab_address(slab), slab->objects) { > + kasan_unpoison_range(addr + offset, > + sizeof(struct slabobj_ext)); Is this leftover from previous version? Otherwise I don't get why we unpoison this. > + memset(addr + offset, 0, sizeof(struct slabobj_ext)); > + } > } > metadata_access_disable(); > }