Messages in this thread | | | Date | Fri, 8 May 2009 11:10:15 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86 MCE: shut up lockdep warning |
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* Andi Kleen <andi@firstfloor.org> wrote:
> On Fri, May 08, 2009 at 11:47:09AM +0800, Shaohua Li wrote: > > lockdep report below warning when I try to offline one cpu: > > [ 110.835487] ================================= > > [ 110.835616] [ INFO: inconsistent lock state ] > > [ 110.835688] 2.6.30-rc4-00336-g8c9ed89 #52 > > [ 110.835757] --------------------------------- > > [ 110.835828] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. > > [ 110.835908] swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes: > > [ 110.835982] (cmci_discover_lock){?.+...}, at: [<ffffffff80236dc0>] cmci_clear+0x30/0x9b > > > > smp_call_function_single() will disable interrupt. moving mce reenable/disable > > to workqueue, so no irq is disabled. > > Looks good. Thanks. > > Acked-by: Andi Kleen <ak@linux.intel.com>
The report is useful, but the fix does not look good at all, and you should never have acked it:
- it works around a lockdep warning
- you did not realize the real bug while the warning was plain
- plus the patch introduces a fragile (because complex) work_on_cpu() call into the CPU hotplug path, which could have caused followup regressions.
Please also Cc: the relevant upstream subsystem maintainers in such cases (the x86 maintaiers in this case).
Thanks,
Ingo
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