Imported xen patches.
[people/pmueller/ipfire-2.x.git] / src / patches / 60066_xen-x86-exit-mmap.patch1
1 Subject: be more aggressive about de-activating mm-s under destruction
2 From: jbeulich@novell.com
3 Patch-mainline: obsolete
4
5 ... by not only handling the current task on the CPU arch_exit_mmap()
6 gets executed on, but also forcing remote CPUs to do so.
7
8 Index: head-2008-12-01/arch/x86/mm/pgtable-xen.c
9 ===================================================================
10 --- head-2008-12-01.orig/arch/x86/mm/pgtable-xen.c 2008-12-01 12:13:06.000000000 +0100
11 +++ head-2008-12-01/arch/x86/mm/pgtable-xen.c 2008-12-01 12:13:16.000000000 +0100
12 @@ -418,27 +418,44 @@ void arch_dup_mmap(struct mm_struct *old
13 mm_pin(mm);
14 }
15
16 -void arch_exit_mmap(struct mm_struct *mm)
17 +/*
18 + * We aggressively remove defunct pgd from cr3. We execute unmap_vmas() *much*
19 + * faster this way, as no hypercalls are needed for the page table updates.
20 + */
21 +static void leave_active_mm(struct task_struct *tsk, struct mm_struct *mm)
22 + __releases(tsk->alloc_lock)
23 {
24 - struct task_struct *tsk = current;
25 -
26 - task_lock(tsk);
27 -
28 - /*
29 - * We aggressively remove defunct pgd from cr3. We execute unmap_vmas()
30 - * *much* faster this way, as no tlb flushes means bigger wrpt batches.
31 - */
32 if (tsk->active_mm == mm) {
33 tsk->active_mm = &init_mm;
34 atomic_inc(&init_mm.mm_count);
35
36 switch_mm(mm, &init_mm, tsk);
37
38 - atomic_dec(&mm->mm_count);
39 - BUG_ON(atomic_read(&mm->mm_count) == 0);
40 + if (atomic_dec_and_test(&mm->mm_count))
41 + BUG();
42 }
43
44 task_unlock(tsk);
45 +}
46 +
47 +static void _leave_active_mm(void *mm)
48 +{
49 + struct task_struct *tsk = current;
50 +
51 + if (spin_trylock(&tsk->alloc_lock))
52 + leave_active_mm(tsk, mm);
53 +}
54 +
55 +void arch_exit_mmap(struct mm_struct *mm)
56 +{
57 + struct task_struct *tsk = current;
58 +
59 + task_lock(tsk);
60 + leave_active_mm(tsk, mm);
61 +
62 + preempt_disable();
63 + smp_call_function_mask(mm->cpu_vm_mask, _leave_active_mm, mm, 1);
64 + preempt_enable();
65
66 if (PagePinned(virt_to_page(mm->pgd))
67 && atomic_read(&mm->mm_count) == 1