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h=Date:From:To:Cc:Subject:References:In-Reply-To; b=hsIquxPo3YGMGU8bVly+ySWIwCtz7VpX7N48Oe57rXA9hkwYB+4/BypRyYw31PusL GqEHOuFLWjk8YwyANJlY6ps9CphdiGMDFWWD3XTLXykR7IP6zPAbBDAyYA9gL7FjGa lCJmVl1nDbglKx7AJS8ow1t5SIwXLZcc16wtXLcnVPwzjL8fkgmkSQ0gbQyEdyz7uc 5py8cF3WvepQpTop22peaQh3M01PMEKR1/mKlhkjN3bNHCOSq1bcEM+HNiSaYY+auk BhHtxqdz0usYhDsnqc2B23gp4cA+DFnF4C/LPUbMRYGYhwIfxtP8y4KwSJPYklx9EG eYnilLva2gk+Q== Date: Thu, 15 Oct 2026 17:18:52 +0100 From: Harry Yoo To: Karl Mehltretter Cc: Vlastimil Babka , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Shengming Hu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/slub: initialize the free pointer of the bootstrap kmem_cache_node Message-ID: References: <20261010203906.93156-1-kmehltretter@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261010203906.93156-1-kmehltretter@gmail.com> X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C4436140007 X-Stat-Signature: w3zt7oxdjxhtjt7ccjt9f1ypdyurtidb X-HE-Tag: 1792081135-938808 X-HE-Meta: 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 CpAzQ6eh 1LOO8dhRkiAYGPe/DdTUcF+ryFgIvxXxWGXOAWGFp19JmDN45YbaRhMYcLoGjcCm5vBNGeB+AxOagOCoa8pGSpvrsevkX26DaAX0Hppy6oJtjlxQG0ERWkq5JwXupVoi6sJfwxBbYRMUap4jVLF7So2WqtI1m4z0mM8ruyoknK2GGMcJTY2lxnknXPrgQF6OVoLgXNmmsZwKbs+RH40P0M39tnvf1QCb6VRGMTP0UvjD+C8y7uq8229xacLnUkGhdmoE91avqrwgZifwJxB+q/s825qTo5SsPE5AIE5rINd7g2xe2jKgmOEm0SrlX3cphvYGfNJAsPdvo1BppC2MIvRVwyw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Oct 10, 2026 at 10:39:06PM +0200, Karl Mehltretter wrote: > With slub_debug=FZPU, validating kmem_cache_node reports > > BUG kmem_cache_node (Not tainted): Freepointer corrupt > Object 0xffff888000140040 @offset=64 fp=0x5a5a5a5a5a5a5a5a > > and taints the kernel. Poisoning places the bootstrap object's free > pointer outside the object, where check_object() checks it even while > allocated. > > early_kmem_cache_node_alloc() previously took this object from a > freelist with an initialized pointer. It now takes it from the slab > iterator and builds the freelist only for the remaining objects, > leaving its pointer filled with POISON_INUSE. > > Initialize the bootstrap object's free pointer to NULL. > > Fixes: dc795d4c0282 ("mm/slub: defer freelist construction until after bulk allocation from a new slab") > Assisted-by: LLM > Signed-off-by: Karl Mehltretter > --- Looks good to me, Reviewed-by: Harry Yoo (Meta) -- Cheers, Harry / Hyeonggon