Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: Suspend on Dell D420 | Date | Sat, 5 Aug 2006 01:26:56 +0200 |
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On Saturday 05 August 2006 00:17, Andrew Morton wrote: > On Fri, 4 Aug 2006 23:27:38 +0200 > "Rafael J. Wysocki" <rjw@sisk.pl> wrote: > > > On Friday 04 August 2006 18:23, Steinar H. Gunderson wrote: > > > [Please Cc me on any followups] > > > > > > Hi, > > > > > > Suspend-to-RAM works fine on my new Dell Latitude D420 (with Core Duo) in > > > 2.6.16, but it broke in 2.6.17 -- the machine suspends just fine, but when it > > > resumes, the disk never spins up, the screen stays black and it just hangs. > > > Bisecting shows that the following commit is where it broke: > > > > > > commit 78eef01b0fae087c5fadbd85dd4fe2918c3a015f > > > Author: Andrew Morton <akpm@osdl.org> > > > Date: Wed Mar 22 00:08:16 2006 -0800 > > > > > > [PATCH] on_each_cpu(): disable local interrupts > > > > > > When on_each_cpu() runs the callback on other CPUs, it runs with local > > > interrupts disabled. So we should run the function with local interrupts > > > disabled on this CPU, too. > > > > > > And do the same for UP, so the callback is run in the same environment on both > > > UP and SMP. (strictly it should do preempt_disable() too, but I think > > > local_irq_disable is sufficiently equivalent). > > > > > > Also uninlines on_each_cpu(). softirq.c was the most appropriate file I could > > > find, but it doesn't seem to justify creating a new file. > > > > > > Oh, and fix up that comment over (under?) x86's smp_call_function(). It > > > drives me nuts. > > > > > > Applying the patch in reverse against 2.6.17 (it doesn't apply cleanly, but > > > I've done what seems to be the moral equivalent) makes the suspend work > > > again. > > > > > > Any ideas? It does not work with the latest git checkout as of today. > > > > I guess the patch may interfere with the CPU hotplug badly. > > Why do you think it would do that?
Because the non-boot CPUs are taken off early, before anything else, and the system is effectively non-SMP during the entire suspend-resume cycle (well, almost). If SMP-related things go wrong during the suspend, CPU hotplug is the first suspect. ;-)
> > Could you please > > check if you can take CPU1 offline/online? > > If something really wants "disable irqs on the other CPUs but not on this > CPU" semantics then it would need to use smp_call_function and a direct > call. But it would be a strange thing to want to do, surely?
Yes, it would, but I have a little experience with these things.
Well, looks like on_each_cpu() is run via flush_tlb_all() from __smp_prepare_cpu() which is called by __cpu_up() and that's used by the CPU hotplug. Not that I can tell what goes wrong here, if anything.
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