Messages in this thread | | | Date | Tue, 19 May 2015 14:57:46 +0200 | From | Petr Mladek <> | Subject | Re: [PATCH v2 00/17] [request for stable 3.10 inclusion] x86/nmi: Print all cpu stacks from NMI safely |
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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
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