preempt bug in set_pmd_pfn?

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To: Ingo Molnar <mingo@...>, H. Peter Anvin <hpa@...>, Andi Kleen <ak@...>
Cc: Linux Kernel Mailing List <linux-kernel@...>
Date: Tuesday, March 4, 2008 - 5:13 pm

I think set_pmd_pfn, which is only called by __set_fixmap, might have a 
preempt bug in it.

It can be executed with preemption enabled, but what if it gets preempted

	set_pmd(pmd, pfn_pmd(pfn, flags));
	/*
	 * It's enough to flush this one mapping.
	 * (PGE mappings get flushed as well)
	 */
	__flush_tlb_one(vaddr);
}

?


Won't this leave a stale tlb on the old processor?

I noticed this because the Xen tlb flushing code effectively has a 
smp_processor_id(), which provokes a warning when preemption is 
enabled.  It seems to me that it never makes sense to be doing a tlb 
flush unless you know which processor you're actually running on...

    J
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Messages in current thread:
preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Tue Mar 4, 5:13 pm)
Re: preempt bug in set_pmd_pfn?, Andi Kleen, (Tue Mar 4, 8:06 pm)
Re: preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Tue Mar 4, 8:07 pm)
Re: preempt bug in set_pmd_pfn?, Andi Kleen, (Tue Mar 4, 8:16 pm)
Re: preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Tue Mar 4, 8:19 pm)
Re: preempt bug in set_pmd_pfn?, Andi Kleen, (Tue Mar 4, 9:28 pm)
Re: preempt bug in set_pmd_pfn?, Ingo Molnar, (Tue Mar 4, 5:28 pm)
Re: preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Tue Mar 4, 5:27 pm)
Re: preempt bug in set_pmd_pfn?, Ingo Molnar, (Wed Mar 5, 2:48 am)
Re: preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Wed Mar 5, 12:45 pm)
Re: preempt bug in set_pmd_pfn?, Hugh Dickins, (Wed Mar 5, 10:29 am)
Re: preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Wed Mar 5, 12:48 pm)
Re: preempt bug in set_pmd_pfn?, Hugh Dickins, (Wed Mar 5, 1:38 pm)
Re: preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Wed Mar 5, 3:18 pm)
Re: preempt bug in set_pmd_pfn?, Ingo Molnar, (Thu Mar 6, 8:52 am)
Re: preempt bug in set_pmd_pfn?, Jeremy Fitzhardinge, (Thu Mar 6, 2:19 pm)
Re: preempt bug in set_pmd_pfn?, Hugh Dickins, (Wed Mar 5, 4:40 pm)