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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2015-08-16 14:27:50 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2017-06-07 19:03:12 -0400 |
| commit | 380c1f0b16211adb80e85a3db62cfcb9e5fff311 (patch) | |
| tree | 761d349a1252d93901b71c156ecebfe0e85b306d | |
| parent | 5f721ca240c91854eaae40c3e9afc4ebd1644fce (diff) | |
| download | linux-rt-380c1f0b16211adb80e85a3db62cfcb9e5fff311.tar.gz | |
dump stack: don't disable preemption during trace
I see here large latencies during a stack dump on x86. The
preempt_disable() and get_cpu() should forbid moving the task to another
CPU during a stack dump and avoiding two stack traces in parallel on the
same CPU. However a stack trace from a second CPU may still happen in
parallel. Also nesting is allowed so a stack trace happens in
process-context and we may have another one from IRQ context. With migrate
disable we keep this code preemptible and allow a second backtrace on
the same CPU by another task.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| -rw-r--r-- | arch/x86/kernel/dumpstack_64.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 66e274a3d968..37aee503a7ba 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -114,7 +114,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, unsigned long *stack, unsigned long bp, const struct stacktrace_ops *ops, void *data) { - const unsigned cpu = get_cpu(); + const unsigned cpu = get_cpu_light(); unsigned long *irq_stack_end = (unsigned long *)per_cpu(irq_stack_ptr, cpu); unsigned used = 0; @@ -191,7 +191,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, * This handles the process stack: */ bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph); - put_cpu(); + put_cpu_light(); } EXPORT_SYMBOL(dump_trace); @@ -205,7 +205,7 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, int cpu; int i; - preempt_disable(); + migrate_disable(); cpu = smp_processor_id(); irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu)); @@ -238,7 +238,7 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, pr_cont(" %016lx", *stack++); touch_nmi_watchdog(); } - preempt_enable(); + migrate_enable(); pr_cont("\n"); show_trace_log_lvl(task, regs, sp, bp, log_lvl); |