| Message ID | 20240426144506.1290619-4-willy@infradead.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Improve anon_vma scalability for anon VMAs | expand |
On Fri, Apr 26, 2024 at 7:45 AM Matthew Wilcox (Oracle) <willy@infradead.org> wrote: > > Rename lock_vma() to uffd_lock_vma() because it really is uffd specific. > Remove comment referencing unlock_vma() which doesn't exist. > Fix the comment about lock_vma_under_rcu() which I just made incorrect. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Suren Baghdasaryan <surenb@google.com> > --- > mm/userfaultfd.c | 20 +++++++++----------- > 1 file changed, 9 insertions(+), 11 deletions(-) > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index e6486923263c..defa5109cc62 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -56,17 +56,16 @@ struct vm_area_struct *find_vma_and_prepare_anon(struct mm_struct *mm, > > #ifdef CONFIG_PER_VMA_LOCK > /* > - * lock_vma() - Lookup and lock vma corresponding to @address. > + * uffd_lock_vma() - Lookup and lock vma corresponding to @address. > * @mm: mm to search vma in. > * @address: address that the vma should contain. > * > - * Should be called without holding mmap_lock. vma should be unlocked after use > - * with unlock_vma(). > + * Should be called without holding mmap_lock. > * > * Return: A locked vma containing @address, -ENOENT if no vma is found, or > * -ENOMEM if anon_vma couldn't be allocated. > */ > -static struct vm_area_struct *lock_vma(struct mm_struct *mm, > +static struct vm_area_struct *uffd_lock_vma(struct mm_struct *mm, > unsigned long address) > { > struct vm_area_struct *vma; > @@ -74,9 +73,8 @@ static struct vm_area_struct *lock_vma(struct mm_struct *mm, > vma = lock_vma_under_rcu(mm, address); > if (vma) { > /* > - * lock_vma_under_rcu() only checks anon_vma for private > - * anonymous mappings. But we need to ensure it is assigned in > - * private file-backed vmas as well. > + * We know we're going to need to use anon_vma, so check > + * that early. > */ > if (!(vma->vm_flags & VM_SHARED) && unlikely(!vma->anon_vma)) > vma_end_read(vma); > @@ -107,7 +105,7 @@ static struct vm_area_struct *uffd_mfill_lock(struct mm_struct *dst_mm, > { > struct vm_area_struct *dst_vma; > > - dst_vma = lock_vma(dst_mm, dst_start); > + dst_vma = uffd_lock_vma(dst_mm, dst_start); > if (IS_ERR(dst_vma) || validate_dst_vma(dst_vma, dst_start + len)) > return dst_vma; > > @@ -1436,7 +1434,7 @@ static int uffd_move_lock(struct mm_struct *mm, > struct vm_area_struct *vma; > int err; > > - vma = lock_vma(mm, dst_start); > + vma = uffd_lock_vma(mm, dst_start); > if (IS_ERR(vma)) > return PTR_ERR(vma); > > @@ -1451,7 +1449,7 @@ static int uffd_move_lock(struct mm_struct *mm, > } > > /* > - * Using lock_vma() to get src_vma can lead to following deadlock: > + * Using uffd_lock_vma() to get src_vma can lead to following deadlock: > * > * Thread1 Thread2 > * ------- ------- > @@ -1473,7 +1471,7 @@ static int uffd_move_lock(struct mm_struct *mm, > err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap); > if (!err) { > /* > - * See comment in lock_vma() as to why not using > + * See comment in uffd_lock_vma() as to why not using > * vma_start_read() here. > */ > down_read(&(*dst_vmap)->vm_lock->lock); > -- > 2.43.0 >
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index e6486923263c..defa5109cc62 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -56,17 +56,16 @@ struct vm_area_struct *find_vma_and_prepare_anon(struct mm_struct *mm, #ifdef CONFIG_PER_VMA_LOCK /* - * lock_vma() - Lookup and lock vma corresponding to @address. + * uffd_lock_vma() - Lookup and lock vma corresponding to @address. * @mm: mm to search vma in. * @address: address that the vma should contain. * - * Should be called without holding mmap_lock. vma should be unlocked after use - * with unlock_vma(). + * Should be called without holding mmap_lock. * * Return: A locked vma containing @address, -ENOENT if no vma is found, or * -ENOMEM if anon_vma couldn't be allocated. */ -static struct vm_area_struct *lock_vma(struct mm_struct *mm, +static struct vm_area_struct *uffd_lock_vma(struct mm_struct *mm, unsigned long address) { struct vm_area_struct *vma; @@ -74,9 +73,8 @@ static struct vm_area_struct *lock_vma(struct mm_struct *mm, vma = lock_vma_under_rcu(mm, address); if (vma) { /* - * lock_vma_under_rcu() only checks anon_vma for private - * anonymous mappings. But we need to ensure it is assigned in - * private file-backed vmas as well. + * We know we're going to need to use anon_vma, so check + * that early. */ if (!(vma->vm_flags & VM_SHARED) && unlikely(!vma->anon_vma)) vma_end_read(vma); @@ -107,7 +105,7 @@ static struct vm_area_struct *uffd_mfill_lock(struct mm_struct *dst_mm, { struct vm_area_struct *dst_vma; - dst_vma = lock_vma(dst_mm, dst_start); + dst_vma = uffd_lock_vma(dst_mm, dst_start); if (IS_ERR(dst_vma) || validate_dst_vma(dst_vma, dst_start + len)) return dst_vma; @@ -1436,7 +1434,7 @@ static int uffd_move_lock(struct mm_struct *mm, struct vm_area_struct *vma; int err; - vma = lock_vma(mm, dst_start); + vma = uffd_lock_vma(mm, dst_start); if (IS_ERR(vma)) return PTR_ERR(vma); @@ -1451,7 +1449,7 @@ static int uffd_move_lock(struct mm_struct *mm, } /* - * Using lock_vma() to get src_vma can lead to following deadlock: + * Using uffd_lock_vma() to get src_vma can lead to following deadlock: * * Thread1 Thread2 * ------- ------- @@ -1473,7 +1471,7 @@ static int uffd_move_lock(struct mm_struct *mm, err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap); if (!err) { /* - * See comment in lock_vma() as to why not using + * See comment in uffd_lock_vma() as to why not using * vma_start_read() here. */ down_read(&(*dst_vmap)->vm_lock->lock);
Rename lock_vma() to uffd_lock_vma() because it really is uffd specific. Remove comment referencing unlock_vma() which doesn't exist. Fix the comment about lock_vma_under_rcu() which I just made incorrect. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- mm/userfaultfd.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-)