Re: x86 ptep_get_and_clear question

[Jamie Lokier <lk@tantalophile.demon.co.uk>]

Ben LaHaise wrote:
> > Processor 2 has recently done some writes, so the dirty bit is set in
> > processor 2's TLB.
> >
> > Processor 1 clears the dirty bit atomically.
> >
> > Processor 2 does some more writes, and does not check the page table
> > because the page is already dirty in its TLB.
> >
> > Result: The later writes on processor 2 do not mark the page dirty.
> 
> Yeah, but the tlb is flushed in those cases (look for flush_tlb_page in
> try_to_swap_out).

As long as processor 1 waits for the flush on processor 2 to complete
before marking the struct page dirty, that looks fine to me.

-- Jamie
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