get_irq_regs only work for current running cpu, but the task, whose
cpuacct will be charged, maybe run different cpu, like Cpu 2 wake
up a kernel thread to CPU 3, cause CPU 3 task are charged with the
following stack
cpuacct_charge+0xd8/0x100
update_curr+0xe1/0x1e0
enqueue_entity+0x144/0x6e0
enqueue_task_fair+0x93/0x900
ttwu_do_activate+0x4b/0x90
try_to_wake_up+0x20b/0x530
? update_dl_rq_load_avg+0x10f/0x210
swake_up_locked.part.1+0x13/0x40
swake_up_one+0x27/0x40
rcu_process_callbacks+0x484/0x4f0
? run_rebalance_domains_bt+0x5a/0x180
__do_softirq+0xe3/0x308
irq_exit+0xf0/0x100
smp_apic_timer_interrupt+0x74/0x160
apic_timer_interrupt+0xf/0x20
</IRQ>
RIP: 0033:0x456947
so define a get_irq_regs_cpu which returns the required cpu irq registers
BUT it should be not safe, and do not know what it should be like in MIPS?
Fixes: dbe9337109c2 "(sched/cpuacct: Fix charge cpuacct.usage_sys)"
Co-developed-by: Zhao Jie <[email protected]>
Signed-off-by: Zhao Jie <[email protected]>
Signed-off-by: Li RongQing <[email protected]>
---
include/asm-generic/irq_regs.h | 5 +++++
kernel/sched/cpuacct.c | 3 ++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/asm-generic/irq_regs.h b/include/asm-generic/irq_regs.h
index 2e7c6e8..93e2579 100644
--- a/include/asm-generic/irq_regs.h
+++ b/include/asm-generic/irq_regs.h
@@ -21,6 +21,11 @@ static inline struct pt_regs *get_irq_regs(void)
return __this_cpu_read(__irq_regs);
}
+static inline struct pt_regs *get_irq_regs_cpu(int cpu)
+{
+ return per_cpu(__irq_regs, cpu);
+}
+
static inline struct pt_regs *set_irq_regs(struct pt_regs *new_regs)
{
struct pt_regs *old_regs;
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 893eece..8b96058 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -340,7 +340,8 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
struct cpuacct *ca;
int index = CPUACCT_STAT_SYSTEM;
- struct pt_regs *regs = get_irq_regs() ? : task_pt_regs(tsk);
+ int cpu = task_cpu(tsk);
+ struct pt_regs *regs = get_irq_regs_cpu(cpu) ? : task_pt_regs(tsk);
if (regs && user_mode(regs))
index = CPUACCT_STAT_USER;
--
2.9.4