Messages in this thread | | | Date | Fri, 8 Jan 2016 10:41:51 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [tip:sched/core] sched/core: Reset task' s lockless wake-queues on fork() |
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On Wed, 6 Jan 2016, tip-bot for Sebastian Andrzej Siewior wrote:
> Commit-ID: 093e5840ae76f1082633503964d035f40ed0216d > Gitweb: http://git.kernel.org/tip/093e5840ae76f1082633503964d035f40ed0216d > Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > AuthorDate: Mon, 21 Dec 2015 18:17:10 +0100 > Committer: Ingo Molnar <mingo@kernel.org> > CommitDate: Wed, 6 Jan 2016 11:01:07 +0100 > > sched/core: Reset task's lockless wake-queues on fork() > > In the following commit: > > 7675104990ed ("sched: Implement lockless wake-queues") > > we gained lockless wake-queues. > > The -RT kernel managed to lockup itself with those. There could be multiple > attempts for task X to enqueue it for a wakeup _even_ if task X is already > running. > > The reason is that task X could be runnable but not yet on CPU. The the > task performing the wakeup did not leave the CPU it could performe > multiple wakeups. > > With the proper timming task X could be running and enqueued for a > wakeup. If this happens while X is performing a fork() then its its > child will have a !NULL `wake_q` member copied. > > This is not a problem as long as the child task does not participate in > lockless wakeups :) > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Cc: Davidlohr Bueso <dbueso@suse.de> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Fixes: 7675104990ed ("sched: Implement lockless wake-queues")
Shouldn't that go into stable?
Thanks,
tglx
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