preempt bug in set_pmd_pfn?

From: Jeremy Fitzhardinge
Date: Tue Mar 04 2008 - 16:19:16 EST


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)
*/
here<
__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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