kdump: crash_kexec()-smp_send_stop() race in panic
holzheu at linux.vnet.ibm.com
Mon Oct 24 10:55:37 EDT 2011
In our tests we ran into the following scenario:
Two CPUs have called panic at the same time. The first CPU called
crash_kexec() and the second CPU called smp_send_stop() in panic()
before crash_kexec() finished on the first CPU. So the second CPU
stopped the first CPU and therefore kdump failed.
panic()->crash_kexec()->mutex_trylock(&kexec_mutex)-> do kdump
panic()->crash_kexec()->kexec_mutex already held by 1st CPU
->smp_send_stop()-> stop CPU 1 (stop kdump)
How should we fix this problem? One possibility could be to do
smp_send_stop() before we call crash_kexec().
What do you think?
More information about the kexec