Messages in this thread | | | Date | Thu, 3 Nov 2005 16:37:14 +0200 | From | "Michael S. Tsirkin" <> | Subject | Re: Nick's core remove PageReserved broke vmware... |
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Quoting Hugh Dickins <hugh@veritas.com>: > Two warnings if someone would like to post a MADV_DONTCOPY patch. > It should include a matching MADV_DOCOPY to clear the condition, but > that must not be allowed to clear VM_DONTCOPY set originally by driver: > perhaps you'll end up with a VM_UDONTCOPY or something like that.
Thanks! All existing drivers that set VM_DONTCOPY also set VM_IO. So lets just disable playing with these flags from madvise if VM_IO is set. There's no reason I can see that the driver should have a say on what the process does with its own (non-IO) memory. Sounds good?
By the way, as a separate issue, we still have a problem with DMA to pages which are *needed* by the child process. What do you think about VM_COPY (to do the old unix thing of actually copying the page instead of setting the COW flag) and a matching madvise call to set/clear it?
> And Badari has a MADV_REMOVE patch in the works, taking the next > slot (just after MADV_DONTNEED in most of the arches): probably > best for you to base yours on top of his (though yours is simpler > and might jump ahead). > > Hugh
Yep, I saw that posted for inclusion in -mm.
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