Kernel Error 6
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Segfault At Ip Sp Error 4
just like you, helping each other. Join them; it only takes a minute: Sign up How do you read a segfault kernel log message up vote 49 down vote favorite 29 This can be a very simple
Segfault Error Codes
question, I'm am attempting to debug an application which generates the following segfault error in the kern.log kernel: myapp[15514]: segfault at 794ef0 ip 080513b sp 794ef0 error 6 in myapp[8048000+24000] Here are my questions: Is there any documentation as to what are the diff error numbers on segfault, in this instance it is error 6, but i've seen error 4, 5 What is the meaning of the information at bf794ef0 ip 0805130b sp bf794ef0 and dmesg segfault error 4 myapp[8048000+24000]? So far i was able to compile with symbols, and when i do a x 0x8048000+24000 it returns a symbol, is that the correct way of doing it? My assumptions thus far are the following: sp = stack pointer? ip = instruction pointer at = ???? myapp[8048000+24000] = address of symbol? c++ c unix segmentation-fault syslog share|improve this question edited Mar 31 '10 at 0:25 Charles Duffy 95.9k15103144 asked Feb 1 '10 at 19:20 Sullenx 246143 Added [unix] [segmentation-fault] [syslog] tags. –Emile Cormier Feb 1 '10 at 19:41 add a comment| 3 Answers 3 active oldest votes up vote 32 down vote Based on my limited knowledge, your assumptions are correct. sp = stack pointer ip = instruction pointer myapp[8048000+24000] = address If I were debugging the problem I would modify the code to produce a core dump or log a stack backtrace on the crash. You might also run the program under (or attach) GDB. The error code is just the architectural error code for page faults and seems to be architecture specific. They are often documented in arch/*/mm/fault.c in the kernel source. My copy of Linux/arch/i386/mm/fault.c has the following definition for error_code: bit 0 == 0 means no page found, 1 means protection fault bit 1 == 0 means read, 1 means write bit 2 ==
you get. So you have a message like the following: segfault at bfea3fec ip 080ee07e sp bfea3fa0 error 6 You might already know that ip means instruction
Segfault Error 14
pointer and sp means stack pointer and as such the addresses that follow segfault at rip rsp error 6 them are the values in those registers. But what does the error number mean? The error number, or code, actually the cause was a user-mode write resulting in no page being found. gives you a better explanation of what the cause of the segfault is. The number's bits are flags describing the error and are architecture-dependent. For x86/x86_64 I just wrote an online converter/decoder http://stackoverflow.com/questions/2179403/how-do-you-read-a-segfault-kernel-log-message that you can use to explain the segfault error code. As an example, the above error code is explained as: The cause was a user-mode write resulting in no page being found. And the common error 4: The cause was a user-mode read resulting in no page being found.(also known as a null pointer dereference). Enjoy. Posted by Raphael Geissert at 02:30 Email ThisBlogThis!Share to https://rgeissert.blogspot.com/2013/07/explaining-segmentation-fault-errors.html TwitterShare to FacebookShare to Pinterest Labels: error, segfault, tool 4 comments: Anonymous12 July 2013 at 15:14Awesome!ReplyDeleteNils14 February 2014 at 10:08Thanks Raphael, just what I needed. ReplyDeleteAnonymous14 July 2014 at 02:14Really nice....Thanks a lotReplyDeleteJwjenkins3614 October 2014 at 20:59thank you!ReplyDeleteAdd commentLoad more... Newer Post Older Post Home Subscribe to: Post Comments (Atom) Popular Posts Explaining segmentation fault errors Editing Debian online with sources.debian.net Debian squeeze LTS Edit Debian, with iceweasel Blog Archive ► 2015 (7) ► August (2) ► June (1) ► May (1) ► April (2) ► January (1) ► 2014 (3) ► December (1) ► April (1) ► March (1) ▼ 2013 (37) ► November (1) ► October (3) ► September (4) ► August (3) ▼ July (2) Ten years-old ebook reader Explaining segmentation fault errors ► June (2) ► May (4) ► April (1) ► March (5) ► February (5) ► January (7) ► 2012 (26) ► December (6) ► November (1) ► October (3) ► September (1) ► July (2) ► June (4) ► May (3) ► April (3) ► March (3) Subscribe Posts Atom Posts Comments Atom Comments Follow by Email Translate Disclaimer Thoughts and opinions expressed in this blog ar
Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the http://serverfault.com/questions/243579/how-to-diagnose-frequent-segfaults workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Server Fault Questions Tags Users Badges Unanswered Ask Question _ Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute: Sign up Here's how segfault error it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top How to diagnose frequent segfaults up vote 4 down vote favorite 2 My server is logging frequent segmentation faults to /var/log/kern.log in different tools. So far I've seen them in Perl, PHP and rsync. All installed software is up-to-date segfault error 4 Debian packages. Here's an exerpt from the log file: Mar 2 01:07:54 gaz kernel: [ 5316.246303] imapsync[4533]: segfault at 8b ip 00007fb448c98fe6 sp 00007ffff571dd68 error 4 in libperl.so.5.10.1[7fb448bd7000+164000] Mar 2 01:17:42 gaz kernel: [ 5904.354307] php5-cgi[4441]: segfault at 2bb3dc8 ip 0000000002bb3dc8 sp 00007fffbeeaae48 error 15 Mar 2 02:54:05 gaz kernel: [11687.922316] php5-cgi[4495]: segfault at 2d7acf9 ip 0000000002d7acf9 sp 00007fff60c6eb18 error 15 Mar 2 10:50:08 gaz kernel: [40250.390322] BUG: unable to handle kernel paging request at 00000000024b03f0 Mar 2 10:50:08 gaz kernel: [40250.390341] IP: [<00000000024b03f0>] 0x24b03f0 Mar 2 10:50:08 gaz kernel: [40250.390353] PGD 208c71067 PUD 21c811067 PMD 209329067 PTE 8000000211c88067 Mar 2 10:50:08 gaz kernel: [40250.390365] Oops: 0011 [#1] SMP Mar 2 10:50:08 gaz kernel: [40250.390373] last sysfs file: /sys/devices/pci0000:00/0000:00:12.0/host4/target4:0:0/4:0:0:0/block/sdb/stat Mar 2 10:50:08 gaz kernel: [40250.390386] CPU 1 Mar 2 10:50:08 gaz kernel: [40250.390392] Modules linked in: cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_conservative xt_recent xt_tcpudp iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ ipv4 ip6table_filter ip6_tables xt_DSCP xt_TCPMSS ipt_LOG ipt_REJECT iptable_mangle iptable_filter xt_multiport xt_state xt_limit xt_conntrack nf_conntrack_ftp nf_conntrack ip_tables x_tables loop snd _hda_codec_atihdmi snd_hda_intel snd_hda_codec snd_hwdep snd_pcm radeon snd_timer ttm snd drm_kms_helper soundcore drm snd_page_a