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Date: Wed, 1 Nov 2017 17:43:14 +0100 From: Oleg Nesterov <oleg@...hat.com> To: Petr Mladek <pmladek@...e.com> Cc: Miroslav Benes <mbenes@...e.cz>, jpoimboe@...hat.com, jeyu@...nel.org, jikos@...nel.org, lpechacek@...e.cz, pavel@....cz, live-patching@...r.kernel.org, linux-kernel@...r.kernel.org, Michael Ellerman <mpe@...erman.id.au>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, linuxppc-dev@...ts.ozlabs.org, x86@...nel.org Subject: Re: [PATCH v3 1/2] livepatch: send a fake signal to all blocking tasks On 11/01, Petr Mladek wrote: > > On Tue 2017-10-31 12:48:52, Miroslav Benes wrote: > > + if (task->flags & PF_KTHREAD) { > > + /* > > + * Wake up a kthread which still has not been migrated. > > + */ > > + wake_up_process(task); > > I have just noticed that freezer used wake_up_state(p, TASK_INTERRUPTIBLE); > IMHO, we should do so as well. I won't argue, but... > wake_up_process() wakes also tasks in TASK_UNINTERRUPTIBLE state. > These might not be ready for an unexpected wakeup. For example, > see concat_dev_erase() in drivers/mtd/mtdcontact.c. I'd say that concat_dev_erase() should be fixed, any code should be ready for spurious wakeup. Note also that wake_up_state(TASK_INTERRUPTIBLE) won't wakeup the TASK_IDLE kthreads, and most of the kthreads which use TASK_INTERRUPTIBLE should use TASK_IDLE today, because in most cases TASK_INTERRUPTIBLE was used to not contribute to loadavg. Oleg.
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