Re: [PATCH] xen: use spin_lock_nest_lock when pinning a pagetable

[Ingo Molnar <mingo@elte.hu>]

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> When pinning/unpinning a pagetable with split pte locks, we can end up
> holding multiple pte locks at once (we need to hold the locks while
> there's a pending batched hypercall affecting the pte page).  Because
> all the pte locks are in the same lock class, lockdep thinks that
> we're potentially taking a lock recursively.
>
> This warning is spurious because we always take the pte locks while
> holding mm->page_table_lock.  lockdep now has spin_lock_nest_lock to
> express this kind of dominant lock use, so use it here so that lockdep
> knows what's going on.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> ---
> arch/x86/xen/mmu.c |   74 +++++++++++++++++++++++++++++++++-------------------
> arch/x86/xen/mmu.h |    3 --
> 2 files changed, 48 insertions(+), 29 deletions(-)

applied to tip/x86/xen, thanks Jeremy!

	Ingo