[PATCH] Xen: Fix pte unpin BUG when !CONFIG_SMP

[Alex Nixon]

We still need to pin PTEs, even if there are no PTE locks.  Otherwise we'll BUG whenever there aren't PTE locks (i.e. whenever NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS), as we try to unpin PTEs which were never pinned in the first place.

Signed-off-by: Alex Nixon <alex.nixon@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
---
 arch/x86/xen/mmu.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index f5af913..1239bda 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -819,9 +819,10 @@ static int xen_pin_page(struct page *page, enum pt_level level)
 					pfn_pte(pfn, PAGE_KERNEL_RO),
 					level == PT_PGD ? UVMF_TLB_FLUSH : 0);
 
-		if (ptl) {
+		if (level == PT_PTE)
 			xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn);
 
+		if (ptl) {
 			/* Queue a deferred unlock for when this batch
 			   is completed. */
 			xen_mc_callback(xen_pte_unlock, ptl);
@@ -924,9 +925,7 @@ static int xen_unpin_page(struct page *page, enum pt_level level)
 		 */
 		if (level == PT_PTE) {
 			ptl = xen_pte_lock(page);
-
-			if (ptl)
-				xen_do_pin(MMUEXT_UNPIN_TABLE, pfn);
+			xen_do_pin(MMUEXT_UNPIN_TABLE, pfn);
 		}
 
 		mcs = __xen_mc_entry(0);
-- 
1.5.4.3

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