Re: [Crash-utility] [PATCH] Fix warning about kernel version inconsistency during crash startup

Hi Lianbo, Thank you for the fix. On 2023/07/21 13:36, Lianbo Jiang wrote: > Currently, the symbol ".rodata" may not be found in some vmlinux, and > the strings command will still be used to get the linux banner string, > but this gets two strings as below: > > # strings /usr/lib/debug/usr/lib/modules/6.5.0-0.rc2.17.fc39.x86_64/vmlinux |grep "Linux version" > Linux version 6.5.0-0.rc2.17.fc39.x86_64 (mockbuild@23a79bad375e4c2c8c60f2d40df7df49) (gcc (GCC) 13.1.1 20230614 (Red Hat 13.1.1-4), GNU ld version 2.40-9.fc39) # SMP PREEMPT_DYNAMIC > Linux version 6.5.0-0.rc2.17.fc39.x86_64 (mockbuild@23a79bad375e4c2c8c60f2d40df7df49) (gcc (GCC) 13.1.1 20230614 (Red Hat 13.1.1-4), GNU ld version 2.40-9.fc39) #1 SMP PREEMPT_DYNAMIC Mon Jul 17 14:57:35 UTC 2023 > > In the verify_namelist(), the while-loop will only determine if the > above first string(linux banner) matches and break the loop. But > actually the above second string is correct one. Eventually, crash > startup with the following warning: > > # ./crash -s /usr/lib/debug/usr/lib/modules/6.5.0-0.rc2.17.fc39.x86_64/vmlinux /var/crash/127.0.0.1-2023-07-20-20\:50\:50/vmcore > WARNING: kernel version inconsistency between vmlinux and dumpfile > > # ./crash -s > WARNING: kernel version inconsistency between vmlinux and live memory > > Let's always try to match the correct one, otherwise still prints a > warning as before. > > Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; > --- > kernel.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/kernel.c b/kernel.c > index 546eed95eebd..9801812387bd 100644 > --- a/kernel.c > +++ b/kernel.c > @@ -1375,8 +1375,6 @@ verify_namelist() > buffer3[i++] = *p1++; > buffer3[i] = NULLCHAR; > } > - > - break; > } > pclose(pipe); > I think you are fixing the fallback routine and that's good, but it's better to fix get_linux_banner_from_vmlinux() first if possible. It's much faster. Isn't it possible? What do you see in "sections:" in "help -s"? And probably you can determine the section where linux_banner is located, with the address of linux_banner and KASLR offset. crash> help -s ... sections: .text vma: ffffffff81000000 size: 14686984 .rodata vma: ffffffff82000000 size: 5366231 .pci_fixup vma: ffffffff8251e1e0 size: 14112 ... crash> sym linux_banner ffffffffb5200a40 (D) linux_banner crash> help -D | grep KERNELOFFSET KERNELOFFSET=33200000 crash> eval ffffffffb5200a40 - 0x33200000 hexadecimal: ffffffff82000a40 --> linux_banner is in ".rodata"