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(p200300cbc74fd600c705bc2517b271c9.dip0.t-ipconnect.de. [2003:cb:c74f:d600:c705:bc25:17b2:71c9]) by smtp.gmail.com with ESMTPSA id x18-20020adfdd92000000b0031aeca90e1fsm12117706wrl.70.2023.09.12.00.13.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Sep 2023 00:13:05 -0700 (PDT) Message-ID: <3a37361d-1f3b-c283-3fb0-ab3614e3d38c@redhat.com> Date: Tue, 12 Sep 2023 09:13:04 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH V2 2/2] proc/kcore: Do not try to access unaccepted memory To: Adrian Hunter , "Kirill A. Shutemov" , Borislav Petkov , Andrew Morton , Ard Biesheuvel Cc: Dave Hansen , Vlastimil Babka , Mike Rapoport , Lorenzo Stoakes , Tom Lendacky , Baoquan He , Vivek Goyal , Dave Young , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, kexec@lists.infradead.org References: <20230911112114.91323-1-adrian.hunter@intel.com> <20230911112114.91323-3-adrian.hunter@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230911112114.91323-3-adrian.hunter@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: DDECDC0019 X-Rspam-User: X-Stat-Signature: 5xu4t5q3q8i9s5mqdhsew3m6qwozkuhr X-Rspamd-Server: rspam01 X-HE-Tag: 1694502789-394863 X-HE-Meta: U2FsdGVkX1/rYfdaKbDBm8dbWZRYOVhbIaDUU/+BTo16abfnDlCa8oA6/9urWiqnU34pXNewUX8hFhUU7yg5IeoxhUBH4xkSvLlj9nDE6heDgalsYncHYHJh47sbextfY1F1sXJmu4ckuXL/LO6EivWZctmj7cqHsm3G8t7Y1hmA2dLYliyCBT1uYSm8aORTEr6gXeDkyjdKvyH5JAoQAcVWubMq6V1fk+2EThL6HwCLUUgX4Corq5Ox3du+C83o0gS7G6uCP1DPpwpcdSxvkCh/eFThVOM58Gt5UbghF6L4gEgFIZHDLPTuzz5wooZ3O7oTkkVq6FewNSfJpckR4YK2dbuVP1O1pdRMdSSiv6huyBOnig/x18Q89XeXGe4tGnC3LJYX5mhXuOVMMmudE7sc2bN3QhHvKQHgnPpNJF+SSo1VC3wdpkVULSjuou1rDJq6f/zlS+ALijsU8L60EQnaryAi5y+/+Vh1BK2gwcmxBTJf34KtDTjAXkdzg/WNg2nWZHnkkUn1ZtDoQFpA1LzyI/mrQcGn6R0ILhhg2bJX7ykqrZTgWskeU8Yi5in6ob0QQJkWeMUE9QDMq4XZ8Iw9CahdyKumerdLrHCYUA33iO7nXkHZADySh6Lpak0gdw59q/zXHfbcGT4utmpPJ3MA8BXleHkFPcZ5Ymvq7Ebh24uSR21QSTYFLLKq9nBVoSzJnhYxhGn5aYjwW4Wj7Tj9N22CPJFJXFV14QbyAJE0uVxH0S36tpuj3SavVZ5EGAxFPxVL9gdpM/3NnTojfA0RgD/GJTo+jfjQvrbpYlLkbxiTI457evTlaDN84vtrhdKG+c9db18QTGJOnoXSUgiKyCs6ngeKddVk/EiY8hXbMQg17zWP53Btrj5fZ1wvm9ZANibRBuf99Y3qRseaWpZAtsIJF5t6jGJoh+Glk9NZU3ogc0denRLYkOT5GB69Pg8ulxLnWADIt4ASF+R 3/4G/Qtt vTXs72UpY6YksjiU1YLlKBuSjF7exjmJP3aBij22DaPMapPu0IJAf+sM7wmpRqmdDRl4txNhjvksZPjNOQdrHTtU4aeF+E9unBs4qOwcEzho/H7rWaVXRTvLeg1BgcBWZgo6nZ0kZXVf/p6z2yIsZMHo1tKODzSe0ygP6iIFcAayjIunyBvW2lbSOz8UvpTp0HK0X3M84oMSWJwCkvx6XgNf64K9NXqyJ3T/qJC2pA+id8AP5GMKpShJH7G7VlEyC+EdJOz3cij2eeyxH7ozM2JMyY9XkLFKLc+pi9ay9Zl5SAKXfhrVWOCOtbFo5z3i+jAWqoL4mI0gqsFTOpcsLlZqAI+1+DqAda7OZjD3hgtqgNp12q0pMJ9EQcwNH7WR7x9Xy5Wfkg03gzA+oK8tNQUO93D9QxpG56mA/fSD6/f4cX6iEN98veJHUug== 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 11.09.23 13:21, Adrian Hunter wrote: > Support for unaccepted memory was added recently, refer commit > dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby a virtual > machine may need to accept memory before it can be used. > > Do not try to access unaccepted memory because it can cause the guest to > fail. > > For /proc/kcore, which is read-only and does not support mmap, this means a > read of unaccepted memory will return zeros. > > Signed-off-by: Adrian Hunter > --- > fs/proc/kcore.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > > Changes in V2: > > Change patch subject and commit message > Do not open code pfn_is_unaccepted_memory() > > > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > index 23fc24d16b31..6422e569b080 100644 > --- a/fs/proc/kcore.c > +++ b/fs/proc/kcore.c > @@ -546,7 +546,8 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) > * and explicitly excluded physical ranges. > */ > if (!page || PageOffline(page) || > - is_page_hwpoison(page) || !pfn_is_ram(pfn)) { > + is_page_hwpoison(page) || !pfn_is_ram(pfn) || > + pfn_is_unaccepted_memory(pfn)) { > if (iov_iter_zero(tsz, iter) != tsz) { > ret = -EFAULT; > goto out; Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb