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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1761702260; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=aM/F09QVx4GPfPIsMF79qJ9NKFno9SfH3yZf/+Wb3Q4=; b=YNccw/Brrj60Ymznhn+quzxsoksok+V00LoQGOyoH4Q+qtEC4B97JrnW1LVOha4EqiDScG 1MVaXdaSs4/R7NQO5tEvxYNdP9zpKJ/mPP1+IU0mbH6fnOHXni5Db0Gb4Lc4vWLTiopCiX JZzA/4kwYSLhZy5w8E9niBLNXtimJMg= From: Hao Ge To: Vlastimil Babka , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Suren Baghdasaryan Cc: Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hao Ge , stable@vger.kernel.org Subject: [PATCH v2] codetag: debug: handle existing CODETAG_EMPTY in mark_objexts_empty for slabobj_ext Date: Wed, 29 Oct 2025 09:43:17 +0800 Message-Id: <20251029014317.1533488-1-hao.ge@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Stat-Signature: 8zq9idna1tb4y7nwr7mrs9c4asrs1s35 X-Rspamd-Queue-Id: 15F5280009 X-Rspamd-Server: rspam09 X-HE-Tag: 1761702262-26538 X-HE-Meta: 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 q8lX2eJK 2X4uCvlpogTMMLm7naLmj7qctYliEh8dAZbG3e9Bm+Al8V4F/RlgbUfw8cb4gFVsdmBMmvSRCt5OdqoAwwSNM7rLjwbqog3HyvgJAa4/aaidyvaC82cmr7Jvjet44kYyhUfJTwQvSL483L9nALhpv9vHWVVD0I64Ms1vRJUCC/TcW6MAsqoRFQSJp96nNyDVilva0HyrkmHg39isWbVrJu4t02PV6IdJPPYyud3pmMXZmDRASSXikyUViMF0F7b3EhMBblAxasX7NSWI= 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: From: Hao Ge When alloc_slab_obj_exts() fails and then later succeeds in allocating a slab extension vector, it calls handle_failed_objexts_alloc() to mark all objects in the vector as empty. As a result all objects in this slab (slabA) will have their extensions set to CODETAG_EMPTY. Later on if this slabA is used to allocate a slabobj_ext vector for another slab (slabB), we end up with the slabB->obj_exts pointing to a slabobj_ext vector that itself has a non-NULL slabobj_ext equal to CODETAG_EMPTY. When slabB gets freed, free_slab_obj_exts() is called to free slabB->obj_exts vector. free_slab_obj_exts() calls mark_objexts_empty(slabB->obj_exts) which will generate a warning because it expects slabobj_ext vectors to have a NULL obj_ext, not CODETAG_EMPTY. Modify mark_objexts_empty() to skip the warning and setting the obj_ext value if it's already set to CODETAG_EMPTY. Fixes: 09c46563ff6d ("codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations") Cc: Signed-off-by: Hao Ge --- v2: Update the commit message and code comments for greater accuracy, incorporating Suren's suggestions. Thanks for Suren's help. --- mm/slub.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index d4367f25b20d..589c596163c4 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2046,7 +2046,11 @@ static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) if (slab_exts) { unsigned int offs = obj_to_index(obj_exts_slab->slab_cache, obj_exts_slab, obj_exts); - /* codetag should be NULL */ + + if (unlikely(is_codetag_empty(&slab_exts[offs].ref))) + return; + + /* codetag should be NULL here */ WARN_ON(slab_exts[offs].ref.ct); set_codetag_empty(&slab_exts[offs].ref); } -- 2.25.1