Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [BUG][2.5.66bk9+] - changes to timers still broken - we don't oops anymore | From | Roland Dreier <> | Date | 06 Apr 2003 13:20:28 -0700 |
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>>>>> "Shawn" == Shawn Starr <spstarr@sh0n.net> writes:
Shawn> It just caused sshd to hang. I don't know why Here's what Shawn> strace reports: Sshd is stuck in 'D' and a child in zombie Shawn> state. The machine has been up for 2 days 18 hours 50 mins.
I may have missed some emails on this topic, so I apologize if this objection was already answered. In any case, if you're running with Andrew's patch that added a del_timer_sync to release_dev(), I think I see how that could cause problems. Here's what I said in my previous email:
From looking at workqueue.c (especially the comment in queue_delayed_work() that says "Increase nr_queued so that the flush function knows that there's something pending."), it seems like flush_scheduled_work() should wait until even delayed work is done. Given that, I don't think the del_timer_sync() should be there -- wouldn't flush_scheduled_work() block forever, since nr_queued can never reach 0 now?
Also, I didn't see an answer to the worry I expressed below:
I don't see how it's _ever_ safe to call flush_scheduled_work(). The comment in workqueue.c before flush_workqueue() says "NOTE: if work is being added to the queue constantly by some other context then this function might block indefinitely." But flush_scheduled_work() is flushing the keventd_wq, which other code will definitely add work to. If we're unlucky, flush_scheduled_work() could block forever. Am I just being paranoid?
I admit that flush_scheduled_work() is unlikely to cause problems in most real world situations, but I'd be curious to know if anyone thinks this could ever lead to a livelock under some strange condition.
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