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bh=O4Ru8fyq2qUax/RXRkWJCuIYSsBuJuIiR89K5Axpcu4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kOBgCgRc8rQm1vntzgi5hLvvhvdE6Eqzr9aQp8n229iEe56JnICdaFMX08mh4vHBX LdBLr1tzqUYsqyoo65DUNxPLjx7I2JQ3ngE6bqPug9LmE6aWxgNSniozxkBYOczzui V+63CvojAZFdSoolrBOpiv3lVQGcUfGxvPtBCbC0= Date: Thu, 23 Mar 2023 15:18:50 -0700 From: Andrew Morton To: Muchun Song Cc: glider@google.com, elver@google.com, dvyukov@google.com, jannh@google.com, sjpark@amazon.de, muchun.song@linux.dev, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: kfence: fix handling discontiguous page Message-Id: <20230323151850.e2785b1cff37fba078f26f2b@linux-foundation.org> In-Reply-To: <20230323025003.94447-1-songmuchun@bytedance.com> References: <20230323025003.94447-1-songmuchun@bytedance.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 2E8B240006 X-Stat-Signature: ze975icjmukhgwe11xhja6qzwoi6cdkw X-HE-Tag: 1679609932-225653 X-HE-Meta: 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 W7uKbm/I Uk/CMgUHS9ntWitaVsn/mf2AygNquiXstmooI4iZFJVv06nQfoR+yl2MQDXhxZ7tY1NOxU1NlksGFN1rk4mjWZQPVtRFLjzbu6rCBsIG++jwxCy6oWcKC46lRoCMjP2t6KPkNT1y43EasRDjqLD2/cWiYJzLbCuZQnTPYe0e1biJBfGoPsFmlTy8yDUBE3Q3XY5OdsgpAQAZCgpitCpo200RyUVCwSecxE52x72Rg4TV2GJd+n3KiVjGEkMaPlRALZQdYA3NODZck9riF6WBHfOq/goVXJqlk0/NCLfiz+CWuADWkxwgUOYFoRvS1o/1TVAFSJQfSozkVADFn8JbJMUyuDuQNHopamOm6Uyy4FN2Iv+G9zAEb1A95YhhtEeiE5Yq+8Jm7fqMmRRvuDW8S1IUWlg== 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: On Thu, 23 Mar 2023 10:50:03 +0800 Muchun Song wrote: > The struct pages could be discontiguous when the kfence pool is allocated > via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP. > So, the iteration should use nth_page(). What are the user-visible runtime effects of this flaw? Thanks.