diff options
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ebd996f8710e..bb4a62f4b953 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6784,6 +6784,23 @@ char *trace_user_fault_read(struct trace_user_buf_info *tinfo, do { /* + * It is possible that something is trying to migrate this + * task. What happens then, is when preemption is enabled, + * the migration thread will preempt this task, try to + * migrate it, fail, then let it run again. That will + * cause this to loop again and never succeed. + * On failures, enabled and disable preemption with + * migration enabled, to allow the migration thread to + * migrate this task. + */ + if (trys) { + preempt_enable_notrace(); + preempt_disable_notrace(); + cpu = smp_processor_id(); + buffer = per_cpu_ptr(tinfo->tbuf, cpu)->buf; + } + + /* * If for some reason, copy_from_user() always causes a context * switch, this would then cause an infinite loop. * If this task is preempted by another user space task, it |