Re: [PATCH] mm: disable preemption in apply_to_pte_range

[Jeremy Fitzhardinge]

Jeremy Fitzhardinge wrote:
> commit 79d9c90453a7bc9e7613ae889a97ff6b44ab8380

Scratch that.  This instead.
   J

   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.  (Do it unconditionally after checking we've
   successfully done the allocation to simplify the error handling.)
   
   Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

diff --git a/mm/memory.c b/mm/memory.c
index baa999e..b80cc31 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1718,6 +1718,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,

	BUG_ON(pmd_huge(*pmd));

+	preempt_disable();
	arch_enter_lazy_mmu_mode();

	token = pmd_pgtable(*pmd);
@@ -1729,6 +1730,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
	} while (pte++, addr += PAGE_SIZE, addr != end);

	arch_leave_lazy_mmu_mode();
+	preempt_enable();

	if (mm != &init_mm)
		pte_unmap_unlock(pte-1, ptl);


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