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X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Jun 2025 11:42:59.8839 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b31d260f-ea77-460a-f129-08ddaa6f72c0 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: DB1PEPF00039230.eurprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI0PR08MB10970 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 54AD512000B X-Stat-Signature: wadcg5dy3eez1bd5ixdrua7pcph3inco X-Rspam-User: X-HE-Tag: 1749814990-162564 X-HE-Meta: U2FsdGVkX1/dLpywqrKdEVr+TOfxfxxW1/Wl6JNLurL2S1SQLG9XOE2JpQvDXPmfc/qGfHj19BzlvxwcTkcdrHUnBDePJt+BM/Aj+FKjysqgbyqLRU3RyCOOVHNU/ZgLw0YbjF2ZoDBXB/ZKLgNHRt06Qrx4qZU+UkteMGBoZ7w6UozNG0SJaK6xhKthY9rU5KyHfC37igXbOf5A4NE/WNC5zltEa/5/k+8pMuTaIvSz0oL2ULk1SKgA9ttl38txVocIvxSR+THWTC1SUFJkZ1cKCM5YCsEQY7W/bGDUXND8AiKB6iWZMqtwGnGYnaxmi8Tq+HoWt+s9UljtGIq16eHhRkMGxoE57oOzeh80xphIdBXyX7kZSWfIAIgZzXNtK5YmvmtMPamX2XoSaq1k+w3m5aPWEvXC1tDUqtNGLTgW6gule1v4A0D2SuzY37/IOiL0Nvl/ciqgLJ4AvePp3bYu9Hil7i0nvND/8eKxAGLLeIORouZBWY2k2mGEu3s9laRMVgD7Wtt998XXVRcdPfBqREHKegIkteIr7HDL4708rT86lLD59xn+4ObojxJ44ur0gzxPAhQSWWwsOSBToa5KCzAxa0SjQzvYm0rGoZA1AEBPPAHcGVATDj81yfKjcrtO5O4EAOAwYaXjKklOI+9WH4RRCS7MZisESyR1Ie4AJCQpjxbtzqm7MPrM2i2HB6gFzVaM4P92fNnEbh3iBceTMJcTt0bgxq/O5814OFojRQybOAiubhE9PCkyp4AhsB+mwFcAgA9acyVm9cDZk9aPnkuDgCr13RctZjozcMdCcDfYcrOyaSIkIATt1XAT0y3OtQj+7MPUGTHbf2yEgJyJfirl7bDCQnK8LEk4g/iAASZLIGjUbUZu2Gbu5rRgF17XDKPxQ7QKMFQYr2B/vr4Apd1j60zRvN4RdckjsxapjT23vhh96MRg4FlZUjbEdQhJV9Ax75wXUMUmiDb pTUz4s3p 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 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: Hi Harry, [...] > Allocate slabobj_exts array from this unused space instead of using > kcalloc(), when it is large enough. > > Enjoy the memory savings! > > [ MEMCG=3Dy, MEM_ALLOC_PROFILING=3Dy ] > > Before patch (run updatedb): > Slab: 5815196 kB > SReclaimable: 5042824 kB > SUnreclaim: 772372 kB > > After patch (run updatedb): > Slab: 5748664 kB > SReclaimable: 5041608 kB > SUnreclaim: 707084 kB (-63.75 MiB) > > [ MEMCG=3Dy, MEM_ALLOC_PROFILING=3Dn ] > > Before patch (run updatedb): > Slab: 5637764 kB > SReclaimable: 5042428 kB > SUnreclaim: 595284 kB > > After patch (run updatedb): > Slab: 5598992 kB > SReclaimable: 5042248 kB > SUnreclaim: 560396 kB (-34.07 MiB) > > This saves from hundreds of KiBs up to several tens of MiBs of memory > on my machine, depending on the config and slab memory usage. > > Enjoy the memory savings! Awesome :) [...] > #ifdef CONFIG_SLUB_DEBUG > static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; > static DEFINE_SPINLOCK(object_map_lock); > @@ -1307,7 +1350,15 @@ slab_pad_check(struct kmem_cache *s, struct slab *= slab) > start =3D slab_address(slab); > length =3D slab_size(slab); > end =3D start + length; > - remainder =3D length % s->size; > + > + if (can_alloc_obj_exts_from_leftover(s, slab)) { > + remainder =3D length; > + remainder -=3D obj_exts_offset(s, slab); > + remainder -=3D obj_exts_size(slab); > + } else { > + remainder =3D length % s->size; > + } > + > if (!remainder) > return; > > @@ -2049,6 +2100,21 @@ static noinline void free_slab_obj_exts(struct sla= b *slab) > slab->obj_exts =3D 0; > } What concerns me about this patch is the case where !memcg_kmem_online() an= d MEM_ALLOC_PROFILING is not used. With this patch, obj_ext can still be created even in that situation, and as a result, if data is overwritten in the region previously padded wit= h POISON_INUSE (before the patch), slab_pad_check() may no longer catch it If this's ignorable, feel free toadd : Reviewed-by: Yeoreum Yun -- Sincerely, Yeoreum Yun IMPORTANT NOTICE: The contents of this email and any attachments are confid= ential and may also be privileged. If you are not the intended recipient, p= lease notify the sender immediately and do not disclose the contents to any= other person, use it for any purpose, or store or copy the information in = any medium. Thank you.