On 03/02, Michal Hocko wrote: > > I cannot really comment on the bcache part because I am not familiar > with the code. same here... > > This patch calls flush_signals() in bcache_device_init() if there is > > pending signal for current process. It avoids bcache registration > > failure in system boot up time due to bcache udev rule timeout. > > this sounds like a wrong way to address the issue. Killing the udev > worker is a userspace policy and the kernel shouldn't simply ignore it. Agreed. If nothing else, if a userspace process has pending SIKILL then flush_signals() is very wrong. > Btw. Oleg, I have noticed quite a lot of flush_signals usage in the > drivers land and I have really hard time to understand their purpose. Heh. I bet most if not all users of flush_signals() are simply wrong. > What is the actual valid usage of this function? I thinks it should die... It was used by kthreads, but today signal_pending() == T is only possible if kthread does allow_signal(), and in this case it should probably use kernel_dequeue_signal(). Say, io_sq_thread(). Why does it do if (signal_pending(current)) flush_signals(current); afaics this kthread doesn't use allow_signal/allow_kernel_signal, this means that signal_pending() must be impossible even if this kthread sleeps in TASK_INTERRUPTIBLE state. Add Jens. Oleg.
