mm: allow preemption in apply_to_pte_range

Impact: allow preemption in apply_to_pte_range updates to init_mm

Preemption is now allowed for lazy mmu mode, so don't disable
it for the inner loop of apply_to_pte_range.  This only applies
when doing updates to init_mm; user pagetables are still modified
under the pte lock, so preemption is disabled anyway.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

diff --git a/mm/memory.c b/mm/memory.c
index b80cc31292b1e78199db38644c85f296426ba3a0..baa999e87cd21d2f9e67c8e3b1093bb6831513fb 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1718,7 +1718,6 @@ 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);
@@ -1730,7 +1729,6 @@ 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);