[PATCH] mm: disable preemption in apply_to_pte_range

[Jeremy Fitzhardinge]

commit 79d9c90453a7bc9e7613ae889a97ff6b44ab8380
Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Date:   Thu Feb 12 13:45:34 2009 -0800

   mm: disable preemption in apply_to_pte_range
   
   Lazy mmu mode needs preemption disabled, so if we're apply to
   init_mm (which doesn't require any pte locks), then explicitly
   disable preemption.
   
   Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

diff --git a/mm/memory.c b/mm/memory.c
index baa999e..71b3fb8 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1710,9 +1710,11 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
	pgtable_t token;
	spinlock_t *uninitialized_var(ptl);

-	pte = (mm == &init_mm) ?
-		pte_alloc_kernel(pmd, addr) :
-		pte_alloc_map_lock(mm, pmd, addr, &ptl);
+	if (mm == &init_mm) {
+		preempt_disable();
+		pte = pte_alloc_kernel(pmd, addr);
+	} else
+		pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
	if (!pte)
		return -ENOMEM;

@@ -1732,6 +1734,9 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,

	if (mm != &init_mm)
		pte_unmap_unlock(pte-1, ptl);
+	else
+		preempt_enable();
+
	return err;
}


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