From: Muchun Song songmuchun@bytedance.com

mainline inclusion from mainline-v6.5-rc7 commit dbe9337109c2705f08e6a00392f991eb2d2570a5 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8BN4B CVE: NA

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The user_mode(task_pt_regs(tsk)) always return true for user thread, and false for kernel thread. So it means that the cpuacct.usage_sys is the time that kernel thread uses not the time that thread uses in the kernel mode. We can try get_irq_regs() first, if it is NULL, then we can fall back to task_pt_regs().

Signed-off-by: Muchun Song songmuchun@bytedance.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/20200420070453.76815-1-songmuchun@bytedance.com Signed-off-by: Xia Fukun xiafukun@huawei.com --- kernel/sched/cpuacct.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index 9fbb10383434..254a60c99435 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -5,6 +5,7 @@ * Based on the work by Paul Menage (menage@google.com) and Balbir Singh * (balbir@in.ibm.com). */ +#include <asm/irq_regs.h> #include "sched.h"

/* Time spent by the tasks of the CPU accounting group executing in ... */ @@ -339,7 +340,7 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime) { struct cpuacct *ca; int index = CPUACCT_STAT_SYSTEM; - struct pt_regs *regs = task_pt_regs(tsk); + struct pt_regs *regs = get_irq_regs() ? : task_pt_regs(tsk);

if (regs && user_mode(regs)) index = CPUACCT_STAT_USER;