Re: [PATCH 1/3] kallsyms: embed source file:line info in kernel stack traces

[Sasha Levin <sashal@kernel.org>]

On Wed, Mar 04, 2026 at 09:17:37PM +0100, Helge Deller wrote:
>On 3/3/26 19:21, Sasha Levin wrote:
>>Add CONFIG_KALLSYMS_LINEINFO, which embeds a compact address-to-line
>>lookup table in the kernel image so stack traces directly print source
>>file and line number information:
>>
>>   root@localhost:~# echo c > /proc/sysrq-trigger
>>   [   11.201987] sysrq: Trigger a crash
>>   [   11.202831] Kernel panic - not syncing: sysrq triggered crash
>>   [   11.206218] Call Trace:
>>   [   11.206501]  <TASK>
>>   [   11.206749]  dump_stack_lvl+0x5d/0x80 (lib/dump_stack.c:94)
>>   [   11.207403]  vpanic+0x36e/0x620 (kernel/panic.c:650)
>>   [   11.208565]  ? __lock_acquire+0x465/0x2240 (kernel/locking/lockdep.c:4674)
>>   [   11.209324]  panic+0xc9/0xd0 (kernel/panic.c:787)
>>   [   11.211873]  ? find_held_lock+0x2b/0x80 (kernel/locking/lockdep.c:5350)
>>   [   11.212597]  ? lock_release+0xd3/0x300 (kernel/locking/lockdep.c:5535)
>>   [   11.213312]  sysrq_handle_crash+0x1a/0x20 (drivers/tty/sysrq.c:154)
>>   [   11.214005]  __handle_sysrq.cold+0x66/0x256 (drivers/tty/sysrq.c:611)
>>   [   11.214712]  write_sysrq_trigger+0x65/0x80 (drivers/tty/sysrq.c:1221)
>>   [   11.215424]  proc_reg_write+0x1bd/0x3c0 (fs/proc/inode.c:330)
>>   [   11.216061]  vfs_write+0x1c6/0xff0 (fs/read_write.c:686)
>>   [   11.218848]  ksys_write+0xfa/0x200 (fs/read_write.c:740)
>>   [   11.222394]  do_syscall_64+0xf3/0x690 (arch/x86/entry/syscall_64.c:63)
>>   [   11.223942]  entry_SYSCALL_64_after_hwframe+0x77/0x7f (arch/x86/entry/entry_64.S:121)
>
>As mentioned in the other series, I really like this patch series.
>
>I tested this series again on the parisc architecture, and the relative
>directories are now stripped with this version of your patch.
>IIRC, the previous patch did show the subdirectory names.
>[  132.840382] Backtrace:
>[  132.840382]  [<104254d8>] show_stack+0x50/0x64 (traps.c:212)
>[  132.840382]  [<1041c0c8>] dump_stack_lvl+0x6c/0xa0 (dump_stack.c:122)
>[  132.840382]  [<1041c118>] dump_stack+0x1c/0x2c (dump_stack.c:130)
>[  132.840382]  [<10402218>] vpanic+0x154/0x344 (panic.c:550)
>[  132.840382]  [<10402438>] panic+0x30/0x34 (panic.c:787)
>[  132.840382]  [<10bebea8>] sysrq_handle_crash+0x30/0x34 (rcupdate.h:110)
>[  132.840382]  [<10bec720>] __handle_sysrq+0xc0/0x1e4 (preempt.h:14)

Ugh... Can you confirm that you've build this kernel with O=?

The RFC had a dirty dirty hack around how we turn these absolute paths into
relative ones, but I tried to re-do it so no one would yell at me :)

-- 
Thanks,
Sasha