Messages in this thread | | | Date | Thu, 12 May 2011 00:15:04 +0800 | Subject | Re: [PATCH] ioapic: fix potential resume deadlock | From | Daniel J Blueman <> |
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On 11 May 2011 07:58, Suresh Siddha <suresh.b.siddha@intel.com> wrote: > On Tue, 2011-05-10 at 03:53 -0700, Daniel J Blueman wrote: >> On 10 May 2011 15:35, Ingo Molnar <mingo@elte.hu> wrote: >> > Hm, there must be some other bug here. >> > >> > ioapic entries should be allocated on system bootup and should never really be >> > deallocated. >> > >> > The bug might be in the idea to call to enable_IR_x2apic() on resume - why are >> > ioapic entries reallocated there? That call in default_setup_apic_routing() was >> > introduced some time ago in: >> > >> > fa47f7e52874: x86, x2apic: Simplify apic init in SMP and UP builds >> > >> > and that it results in reallocation in the suspend patch is distinctly wrong. >> > >> > I suspect the reason why this has not triggered for others is the relative >> > rarity of affected systems? >> > >> > Suresh? > > This will happen only on interrupt-remapping enabled systems and hence > hidden so far. > > enable_IR_x2apic() / default_setup_apic_routing() routines don't get > called during resume. Problem is with the lapic_resume() path which is > trying to re-enable x2apic mode and this requires masking io-apic > entries, re-enabling x2apic and interrupt-remapping, restoring io-apic > entries etc. ioapic entry allocation that is happening in lapic_resume() > is just for storing the original io-apic RTE's during the mask/restore > operations that happen around re-enabling x2apic. > > Anyways looking at that code, there is some duplicate code between > x2apic code and the io-apic suspend/resume sequence. So a better fix > will be to remove this duplicate code. > > Daniel, I appended a quick patch which should fix the problem you > reported. This is not a final patch, as I can do some more cleanup and > re-use the io-apic suspend/resume code a bit more. > > If this patch works for you, then I can spend some more time to do the > complete cleanup patch in a day or two. Thanks. [...]
Superb, this works, tested against 2.6.39-rc7 and addresses the "BUG: sleeping function called from invalid context at mm/slub.c:824" warning I was previously seeing. It would be good to get this fix into 2.6.39-final if possible.
Tested-by: Daniel J Blueman <daniel.blueman@gmail.com>
Thanks, Daniel -- Daniel J Blueman -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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