From bd92883051a0228cc34996b8e766111ba10c9aac Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 6 Apr 2016 21:59:50 +1000 Subject: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() task_pt_regs() can return NULL for kernel threads, so add a check. This fixes an oops at boot on ppc64. Reported-and-Tested-by: Srikar Dronamraju Tested-by: Zhao Lei Signed-off-by: Anton Blanchard Acked-by: Zhao Lei Cc: Linus Torvalds Cc: Michael Ellerman Cc: Peter Zijlstra Cc: Stephen Rothwell Cc: Thomas Gleixner Cc: efault@gmx.de Cc: htejun@gmail.com Cc: linuxppc-dev@lists.ozlabs.org Cc: tj@kernel.org Cc: yangds.fnst@cn.fujitsu.com Link: http://lkml.kernel.org/r/20160406215950.04bc3f0b@kryten Signed-off-by: Ingo Molnar --- kernel/sched/cpuacct.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index df947e07aac1..41f85c4d0938 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -316,12 +316,11 @@ static struct cftype files[] = { void cpuacct_charge(struct task_struct *tsk, u64 cputime) { struct cpuacct *ca; - int index; + int index = CPUACCT_USAGE_SYSTEM; + struct pt_regs *regs = task_pt_regs(tsk); - if (user_mode(task_pt_regs(tsk))) + if (regs && user_mode(regs)) index = CPUACCT_USAGE_USER; - else - index = CPUACCT_USAGE_SYSTEM; rcu_read_lock();