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[91.12.103.241]) by smtp.gmail.com with ESMTPSA id h4sm12872990wrm.42.2021.08.16.10.54.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Aug 2021 10:54:25 -0700 (PDT) Subject: Re: [BUG] general protection fault when reading /proc/kcore From: David Hildenbrand To: Jiri Olsa , Mike Rapoport , Andrew Morton , Oscar Salvador Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <1a05d147-e249-7682-2c86-bbd157bc9c7d@redhat.com> Organization: Red Hat Message-ID: Date: Mon, 16 Aug 2021 19:54:24 +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: <1a05d147-e249-7682-2c86-bbd157bc9c7d@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 16.08.21 19:49, David Hildenbrand wrote: > 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 Sorry, missed the /proc/kcore part: [root@localhost ~]# cat /proc/kallsyms | grep ksys_read ffffffffba27a800 T ksys_readahead ffffffffba333660 T ksys_read [root@localhost ~]# objdump -d --start-address=0xffffffffba333660 --stop-address=0xffffffffba333670 /proc/kcore /proc/kcore: file format elf64-x86-64 Disassembly of section load1: ffffffffba333660 : ffffffffba333660: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) ffffffffba333665: 41 55 push %r13 ffffffffba333667: 49 89 d5 mov %rdx,%r13 ffffffffba33366a: 41 54 push %r12 ffffffffba33366c: 49 89 f4 mov %rsi,%r12 ffffffffba33366f: 55 push %rbp -- Thanks, David / dhildenb