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authorJeremy Fitzhardinge <jeremy@xensource.com>2007-10-16 14:51:30 -0400
committerJeremy Fitzhardinge <jeremy@goop.org>2007-10-16 14:51:30 -0400
commit74260714c56de4f967fcb2f17a8656bc574b75be (patch)
treef02bcd991285a20a543fae69f916577c8447b8f4 /Kbuild
parent9f79991d4186089e228274196413572cc000143b (diff)
xen: lock pte pages while pinning/unpinning
When a pagetable is created, it is made globally visible in the rmap prio tree before it is pinned via arch_dup_mmap(), and remains in the rmap tree while it is unpinned with arch_exit_mmap(). This means that other CPUs may race with the pinning/unpinning process, and see a pte between when it gets marked RO and actually pinned, causing any pte updates to fail with write-protect faults. As a result, all pte pages must be properly locked, and only unlocked once the pinning/unpinning process has finished. In order to avoid taking spinlocks for the whole pagetable - which may overflow the PREEMPT_BITS portion of preempt counter - it locks and pins each pte page individually, and then finally pins the whole pagetable. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickens <hugh@veritas.com> Cc: David Rientjes <rientjes@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andi Kleen <ak@suse.de> Cc: Keir Fraser <keir@xensource.com> Cc: Jan Beulich <jbeulich@novell.com>
Diffstat (limited to 'Kbuild')
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