On Tue 2015-05-19 09:08:45, Wang Long wrote: > This is my backport patch series to Fix the problem(backport to 3.10): > " > When trigger_all_cpu_backtrace() is called on x86, it will trigger an > NMI on each CPU and call show_regs(). But this can lead to a hard lock > up if the NMI comes in on another printk(). > " > The solution is described in commit "a9edc88093287183ac934be44f295f183b2c62dd": > when the NMI triggers, it switches the printk routine for that CPU to call > a NMI safe printk function that records the printk in a per_cpu seq_buf > descriptor. After all NMIs have finished recording its data, the trace_ > seqs are printed in a safe context. > > The solution use "switch printk routine" and "seq_buf" infrastructures, but the > 3.10 stable have no both of them. > > The patch 1-13 backport the "seq_buf" infrastructures. in detail, patch 1, 2 > and 6 only backport "seq_buf" related code. > > The patch 14-15 backport the "switch printk routine". > > The patch 16-17 is the patch to print all cpu stacks from NMI safely > > as discussed in https://lkml.org/lkml/2015/5/13/497, in 3.10 stable, this is > the only way to solve the problem and the backport code is a bit more. > > v1 -> v2: > * fix the indent error. > * rebase on 3.10.79 > > Any thoughts? Please, wait with the integration. I am testing it with a storm of sysrq requests: $> while true ; do echo l >/proc/sysrq-trigger ; done with iptables enabled: $> iptables -A INPUT -j LOG --log-prefix "incomming packet:" and storm of pings from other machine: $> ping -f <patched-host> The machine somehow freezes. It does not make sense. I am trying to investigate. Best Regards, Petr -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html