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    Subject[RFC][PATCH 8/7] lockdep: annotate mm_take_all_locks()
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    Date
    Subject: lockdep: annotate mm_take_all_locks()

    The nesting is correct due to holding mmap_sem, use the new annotation
    to annotate this.

    This doesn't solve the MAX_LOCK_DEPTH issue, but 48 seems enough for
    the current kvm usage, which does this early on in the life of an mm.

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    ---
    mm/mmap.c | 12 ++++++------
    1 file changed, 6 insertions(+), 6 deletions(-)

    Index: linux-2.6/mm/mmap.c
    ===================================================================
    --- linux-2.6.orig/mm/mmap.c
    +++ linux-2.6/mm/mmap.c
    @@ -2273,14 +2273,14 @@ int install_special_mapping(struct mm_st

    static DEFINE_MUTEX(mm_all_locks_mutex);

    -static void vm_lock_anon_vma(struct anon_vma *anon_vma)
    +static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
    {
    if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
    /*
    * The LSB of head.next can't change from under us
    * because we hold the mm_all_locks_mutex.
    */
    - spin_lock(&anon_vma->lock);
    + spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
    /*
    * We can safely modify head.next after taking the
    * anon_vma->lock. If some other vma in this mm shares
    @@ -2296,7 +2296,7 @@ static void vm_lock_anon_vma(struct anon
    }
    }

    -static void vm_lock_mapping(struct address_space *mapping)
    +static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
    {
    if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
    /*
    @@ -2310,7 +2310,7 @@ static void vm_lock_mapping(struct addre
    */
    if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
    BUG();
    - spin_lock(&mapping->i_mmap_lock);
    + spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
    }
    }

    @@ -2359,9 +2359,9 @@ int mm_take_all_locks(struct mm_struct *
    if (signal_pending(current))
    goto out_unlock;
    if (vma->anon_vma)
    - vm_lock_anon_vma(vma->anon_vma);
    + vm_lock_anon_vma(mm, vma->anon_vma);
    if (vma->vm_file && vma->vm_file->f_mapping)
    - vm_lock_mapping(vma->vm_file->f_mapping);
    + vm_lock_mapping(mm, vma->vm_file->f_mapping);
    }
    ret = 0;




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