Re: [Crash-utility] [PATCH] crash extension: trace

On Mar 22, 2021, at 8:12 PM, d.hatayama@fujitsu.com<mailto:d.hatayama@fujitsu.com> wrote: Wengang, Thanks for your patch. From a UEK5 vmcore, I see that What arch and kernel version do you use? What is the last kernel version you didn't see this issue? It’s Oracle Unbreakable Enterprise Kernel V5 for X86_64, source code is based on 4.14 mainline stable kernel. That is the latest kernel I tried. Thanks, Wengang I need to identify the change in the kernel side that caused this issue. crash> p &__start___trace_bprintk_fmt $1 = (const char *(*)[]) 0xffffffffa163f1d0 crash> p &__stop___trace_bprintk_fmt $2 = (const char *(*)[]) 0xffffffffa163f1f0 so (0xffffffffa163f1f0 - 0xffffffffa163f1d0)/8 = 4. there are two zero addresses at index 2 and 3. crash> rd __start___trace_bprintk_fmt 4 ffffffffa163f1d0: ffffffffa11ccdca ffffffffa11ccdca ................ ffffffffa163f1e0: 0000000000000000 0000000000000000 ................ current implementation will fail (no output for trace show command) on seeing the zero addresses. fix: ignore zero addresses in add_print_address. tested to be good (compared the ftrace log from vmcore and that from live system). Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com<mailto:wen.gang.wang@oracle.com>> Thanks. HATAYAMA, Daisuke