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[91.12.103.241]) by smtp.gmail.com with ESMTPSA id l2sm11417288wrx.2.2021.08.16.10.49.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Aug 2021 10:49:16 -0700 (PDT) To: Jiri Olsa , Mike Rapoport , Andrew Morton , Oscar Salvador Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: From: David Hildenbrand Organization: Red Hat Subject: Re: [BUG] general protection fault when reading /proc/kcore Message-ID: <1a05d147-e249-7682-2c86-bbd157bc9c7d@redhat.com> Date: Mon, 16 Aug 2021 19:49:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.08.21 19:34, Jiri Olsa wrote: > hi, > I'm getting fault below when running: > > # cat /proc/kallsyms | grep ksys_read > ffffffff8136d580 T ksys_read > # objdump -d --start-address=0xffffffff8136d580 --stop-address=0xffffffff8136d590 /proc/kcore > > /proc/kcore: file format elf64-x86-64 > > Segmentation fault > > any idea? config is attached Just tried with a different config on 5.14.0-rc6+ [root@localhost ~]# cat /proc/kallsyms | grep ksys_read ffffffff8927a800 T ksys_readahead ffffffff89333660 T ksys_read [root@localhost ~]# objdump -d --start-address=0xffffffff89333660 --stop-address=0xffffffff89333670 a.out: file format elf64-x86-64 The kern_addr_valid(start) seems to fault in your case, which is weird, because it merely walks the page tables. But it seems to complain about a non-canonical address 0xf887ffcbff000 Can you post your QEMU cmdline? Did you test this on other kernel versions? Thanks! -- Thanks, David / dhildenb