https://jira.whamcloud.com This file is an XML representation of an issue en-us 9.4.14 940014 05-12-2023 https://jira.whamcloud.com/browse/LU-9698 Lustre <p>Running <tt>llmount.sh</tt> from master with a patched kernel fails with:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>$&gt; llmount.sh [...] insmod: error inserting '/home/user/lustre-release/lustre/tests/../osd-ldiskfs/osd_ldiskfs.ko': -1 Unknown symbol in module </pre> </div></div> <p>Output of dmesg:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>$&gt; dmesg | tail -1 osd_diskfs Unknown symbol kallsyms_lookup_name (err 0) </pre> </div></div> <p>The problem appears after commit 0f0a43b</p> Centos6 - patched kernel LU-9698

osd-ldiskfs: unknown symbol error on patched kernel

Bug Minor Resolved Won't Fix Oleg Drokin CEA Wed, 21 Jun 2017 08:01:03 +0000 Wed, 5 Aug 2020 13:50:22 +0000 Mon, 18 Sep 2017 12:26:03 +0000 0 9 <p>Oleg</p> <p>Could you please advise?</p> <p>Thanks</p> <p>Peter</p> <p>That's really strange.<br/> What's your kernel config esp. in relation to CONFIG_KALLSYMS* ?<br/> LLNL builder built the patch that introduced this and it pass: <a href="https://review.whamcloud.com/#/c/27549/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/#/c/27549/</a><br/> <a href="http://build.lustre.org/builders/CentOS%206.8%20x86_64%20%28BUILD%29/builds/5549" class="external-link" target="_blank" rel="nofollow noopener">http://build.lustre.org/builders/CentOS%206.8%20x86_64%20%28BUILD%29/builds/5549</a></p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>$&gt; cat /boot/config-2.6.32.573.18.1.el6_lustre | grep KALLSYM CONFIG_KALLSYMS=y CONFIG_KALLSYMS_ALL=y CONFIG_KALLSYMS_EXTRA_PASS=y </pre> </div></div> <p>It builds alright on my machine, it's just the insmod part that doesn't work. I don't know if LLNL builder tries to run <tt>llmount.sh</tt>, it if does, it is indeed strange...<br/> For the record, I patched the kernel myself following the procedure on the wiki a while ago.</p> <p>Hm, so I just looked and it appears that kallsyms_lookup_name is just not exported on rhel6 at all.<br/> I guess we can have a configure check to totally disable this functionality on rhel6 esp since on master we don't really support rhel6 anymore.</p> <p>&gt; esp since on master we don't really support rhel6 anymore</p> <p>I'll switch to rhel7 then =]</p> <p>Oleg Drokin (oleg.drokin@intel.com) uploaded a new patch: <a href="https://review.whamcloud.com/27874" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/27874</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-9698" title="osd-ldiskfs: unknown symbol error on patched kernel" class="issue-link" data-issue-key="LU-9698"><del>LU-9698</del></a> osd-ldiskfs: See if kallsyms_lookup_name is exported<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 38e08695753f0511c2cab5109a2411ef43495ad1</p> <p>It looks like RHEL6 has <tt>EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol)</tt> that could be used for doing the symbol lookup, like:</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">#ifndef HAVE_KALLSYMS_LOOKUP_NAME <span class="code-object">int</span> kallsyms_strcmp(void *name, <span class="code-keyword">const</span> <span class="code-object">char</span> *symbol_name, struct module *, unsigned <span class="code-object">long</span> symbol_address) { <span class="code-keyword">return</span> strcmp(name, symbol_name) == 0 ? symbol_address : 0; } /* Note that kallsyms_strcmp() cannot <span class="code-keyword">return</span> the full symbol address, only the low 32 bits. * We can handle <span class="code-keyword">this</span> by extracting the high word from some other kernel function */ unsigned <span class="code-object">long</span> ll_kallsyms_lookup_name(<span class="code-keyword">const</span> <span class="code-object">char</span> *name) { unsigned <span class="code-object">int</span> low_addr = kallsyms_on_each_symbol(kallsyms_strcmp, name); <span class="code-keyword">return</span> low_addr ? kallsyms_on_each_symbol &amp; 0xffffffff00000000ULL | low_addr : 0; } #<span class="code-keyword">else</span> #define ll_kallsyms_lookup_name(name) kallsyms_lookup_name(name) #endif </pre> </div></div> <p>Now that <a href="https://review.whamcloud.com/28029" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/28029</a> which Bob had RHEL6.9 kernel include a patch to export kallsyms when build RHEL kernel. This is fine since RHEL6 kernels will never be patchless like RHEL7 kernels. We should be able to close this since this is the case?</p> <p>I agree James</p> Related LU-20 Development Rank 1|hzzfhj: Rank (Obsolete) 9223372036854775807 Severity