Messages in this thread | | | Date | Thu, 15 Feb 2007 23:24:47 -0800 | From | Andrew Morton <> | Subject | Re: [patch 12/21] Xen-paravirt: Allocate and free vmalloc areas |
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On Thu, 15 Feb 2007 23:08:02 -0800 Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Andrew Morton wrote: > > This won't work when CONFIG_PREEMPT=y. The pagefault handler will see > > in_atomic() and will scram. > > > > Is there some other way to get the pagetable populated for the address > range? >
If you really need to run atomically, that gets ugly. Even of one were to run handle_mm_fault() by hand, it still needs to allocate memory.
Two ugly options might be:
a) touch all the pages, then go atomic, then touch them all again. If one of them faults (ie: you raced with swapout) then go back and try again. Obviously susceptible to livelocking.
b) Do get_user_pages() against all the pages, then go atomic, then do put_page() against them all. Of course, they can immediately get swapped out.
But that function's already racy against swapout and I guess it works OK. I don't have clue what it is actually trying to do, so I'm guessing madly here. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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