Hi Hoeun, On 04/08/17 08:02, Hoeun Ryu wrote: > Commit 0ee5941 : (x86/panic: replace smp_send_stop() with kdump friendly > version in panic path) introduced crash_smp_send_stop() which is a weak > function and can be overriden by architecture codes to fix the side effect > caused by commit f06e515 : (kernel/panic.c: add "crash_kexec_post_ > notifiers" option).
If I've understood correctly: if we boot with this option core code doesn't use our machine_crash_shutdown(), and instead calls crash_smp_send_stop(), which we don't have, so it uses the default smp_send_stop(), which doesn't save the regs. Thanks for catching this! Could we rename smp_send_crash_stop() crash_smp_send_stop() and add the called-twice logic there? They are similar enough that I'm getting them muddled already! Thanks, James > ARM64 architecture uses the weak version function and the problem is that > the weak function simply calls smp_send_stop() which makes other CPUs > offline and takes away the chance to save crash information for nonpanic > CPUs in machine_crash_shutdown() when crash_kexec_post_notifiers kernel > option is enabled. > > Calling smp_send_crash_stop() in the function is useless because all > nonpanic CPUs are already offline by smp_send_stop() in this case and > smp_send_crash_stop() only works against online CPUs. > > The result is that /proc/vmcore is not available with the error messages; > "Warning: Zero PT_NOTE entries found", "Kdump: vmcore not initialized". > > crash_smp_send_stop() is implemented for ARM64 architecture to fix this > problem and the function (strong symbol version) saves crash information > for nonpanic CPUs using smp_send_crash_stop() and machine_crash_shutdown() > tries to save crash information for nonpanic CPUs only when > crash_kexec_post_notifiers kernel option is disabled.