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Groups > linux.kernel > #1377855

[tip:sched/core] sched/cpuacct: Check for NULL when using task_pt_regs()

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Commit-ID:  bd92883051a0228cc34996b8e766111ba10c9aac
Gitweb:     http://git.kernel.org/tip/bd92883051a0228cc34996b8e766111ba10c9aac
Author:     Anton Blanchard <anton@samba.org>
AuthorDate: Wed, 6 Apr 2016 21:59:50 +1000
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 13 Apr 2016 13:22:37 +0200

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 <srikar@linux.vnet.ibm.com>
Tested-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
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 <mingo@kernel.org>
---
 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 df947e0..41f85c4 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();
 

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Re: [tip:sched/core] sched/cpuacct: Split usage accounting into  user_usage and sys_usage Srikar Dronamraju <srikar@linux.vnet.ibm.com> - 2016-04-04 16:10 +0200
  Re: [tip:sched/core] sched/cpuacct: Split usage accounting into  user_usage and sys_usage Ingo Molnar <mingo@kernel.org> - 2016-04-06 09:00 +0200
    RE: [tip:sched/core] sched/cpuacct: Split usage accounting into user_usage and sys_usage Zhao Lei <zhaolei@cn.fujitsu.com> - 2016-04-06 09:50 +0200
      Re: [tip:sched/core] sched/cpuacct: Split usage accounting into  user_usage and sys_usage Peter Zijlstra <peterz@infradead.org> - 2016-04-06 10:00 +0200
    Re: [tip:sched/core] sched/cpuacct: Split usage accounting into  user_usage and sys_usage Anton Blanchard <anton@samba.org> - 2016-04-06 12:40 +0200
      Re: [tip:sched/core] sched/cpuacct: Split usage accounting into  user_usage and sys_usage Peter Zijlstra <peterz@infradead.org> - 2016-04-06 13:10 +0200
        RE: [tip:sched/core] sched/cpuacct: Split usage accounting into user_usage and sys_usage Zhao Lei <zhaolei@cn.fujitsu.com> - 2016-04-06 13:50 +0200
        [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Anton Blanchard <anton@samba.org> - 2016-04-06 14:10 +0200
          Re: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Srikar Dronamraju <srikar@linux.vnet.ibm.com> - 2016-04-06 16:40 +0200
            RE: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Zhao Lei <zhaolei@cn.fujitsu.com> - 2016-04-06 19:10 +0200
            Re: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Ingo Molnar <mingo@kernel.org> - 2016-04-13 09:50 +0200
              Re: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Michael Ellerman <mpe@ellerman.id.au> - 2016-04-13 13:10 +0200
                Re: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Ingo Molnar <mingo@kernel.org> - 2016-04-13 13:30 +0200
          Ping? Re: [PATCH] sched/cpuacct: Check for NULL when using  task_pt_regs() Michael Ellerman <mpe@ellerman.id.au> - 2016-04-11 08:20 +0200
          [tip:sched/core] sched/cpuacct: Check for NULL when using  task_pt_regs() tip-bot for Anton Blanchard <tipbot@zytor.com> - 2016-04-13 14:00 +0200

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