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[2003:cb:c709:6300:a751:d742:1f76:8639]) by smtp.gmail.com with ESMTPSA id u7sm2354316wrq.112.2022.02.07.06.33.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Feb 2022 06:33:34 -0800 (PST) Message-ID: <6d4ab70e-b944-5f7d-e9a3-979ac66c70f7@redhat.com> Date: Mon, 7 Feb 2022 15:33:34 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH] mm/memory_hotplug: fix kfree() of bootmem memory To: Miaohe Lin , akpm@linux-foundation.org Cc: isimatu.yasuaki@jp.fujitsu.com, toshi.kani@hp.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220207135618.17231-1-linmiaohe@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220207135618.17231-1-linmiaohe@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 684A64000D X-Stat-Signature: 6tbtr7kpp4gscuuzpqmcf9qcz9dyfrzh Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=hdwdP0jl; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf04.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com X-Rspam-User: nil X-HE-Tag: 1644244418-975561 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 07.02.22 14:56, Miaohe Lin wrote: > We can't use kfree() to release the resource as it might come from bootmem. > Use release_mem_region() instead. How can this happen? release_mem_region() is called either from __add_memory() or from add_memory_driver_managed(), where we allocated the region via register_memory_resource(). Both functions shouldn't ever be called before the buddy is up an running. Do you have a backtrace of an actual instance of this issue? Or was this identified as possibly broken by code inspection? -- Thanks, David / dhildenb