Commit c7617798 authored Jan 18, 2011 by Konrad Rzeszutek Wilk

xen/mmu: WARN_ON when racing to swap middle leaf.



The initial bootup code uses set_phys_to_machine quite a lot, and after
bootup it would be used by the balloon driver. The balloon driver does have
mutex lock so this should not be necessary - but just in case, add
a WARN_ON if we do hit this scenario. If we do fail this, it is OK
to continue as there is a backup mechanism (VM_IO) that can bypass
the P2M and still set the _PAGE_IOMAP flags.

[v2: Change from WARN to BUG_ON]
[v3: Rebased on top of xen->p2m code split]
[v4: Change from BUG_ON to WARN]
Reviewed-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

parent fb38923e

arch/x86/xen/p2m.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -605,7 +605,8 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)

		/* Swap over from MISSING to IDENTITY if needed. */
		if (p2m_top[topidx][mididx] == p2m_missing) {
		p2m_top[topidx][mididx] = p2m_identity;
		WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
		p2m_identity) != p2m_missing);
		return true;
		}
		}

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