From: Steven Rostedt (Red Hat) Date: Thu, 19 Jun 2014 21:33:32 +0000 (-0400) Subject: x86/nmi: Perform a safe NMI stack trace on all CPUs X-Git-Tag: omap-for-v3.19/fixes-rc1~139^2~2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a9edc88093287183ac934be44f295f183b2c62dd;p=pandora-kernel.git x86/nmi: Perform a safe NMI stack trace on all CPUs 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(). In order to avoid this, 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 seq_bufs are printed in a safe context. Link: http://lkml.kernel.org/p/20140619213952.360076309@goodmis.org Link: http://lkml.kernel.org/r/20141115050605.055232587@goodmis.org Tested-by: Jiri Kosina Acked-by: Jiri Kosina Acked-by: Paul E. McKenney Reviewed-by: Petr Mladek Signed-off-by: Steven Rostedt --- Reading git-diff-tree failed