Thanks Minchan! On Thu, Aug 23, 2018 at 7:29 AM, Minchan Kim <minchan@xxxxxxxxxx> wrote: > Signed-off-by: Todd Kjos <tkjos@xxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Reviewed-by: Martijn Coenen <maco@xxxxxxxxxxx> > --- > drivers/android/binder_alloc.c | 43 +++++++++++++++++++++++++++------- > 1 file changed, 35 insertions(+), 8 deletions(-) > > diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c > index 3f3b7b253445..64fd96eada31 100644 > --- a/drivers/android/binder_alloc.c > +++ b/drivers/android/binder_alloc.c > @@ -332,6 +332,35 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate, > return vma ? -ENOMEM : -ESRCH; > } > > + > +static inline void binder_alloc_set_vma(struct binder_alloc *alloc, > + struct vm_area_struct *vma) > +{ > + if (vma) > + alloc->vma_vm_mm = vma->vm_mm; > + /* > + * If we see alloc->vma is not NULL, buffer data structures set up > + * completely. Look at smp_rmb side binder_alloc_get_vma. > + * We also want to guarantee new alloc->vma_vm_mm is always visible > + * if alloc->vma is set. > + */ > + smp_wmb(); > + alloc->vma = vma; > +} > + > +static inline struct vm_area_struct *binder_alloc_get_vma( > + struct binder_alloc *alloc) > +{ > + struct vm_area_struct *vma = NULL; > + > + if (alloc->vma) { > + /* Look at description in binder_alloc_set_vma */ > + smp_rmb(); > + vma = alloc->vma; > + } > + return vma; > +} > + > static struct binder_buffer *binder_alloc_new_buf_locked( > struct binder_alloc *alloc, > size_t data_size, > @@ -348,7 +377,7 @@ static struct binder_buffer *binder_alloc_new_buf_locked( > size_t size, data_offsets_size; > int ret; > > - if (alloc->vma == NULL) { > + if (!binder_alloc_get_vma(alloc)) { > binder_alloc_debug(BINDER_DEBUG_USER_ERROR, > "%d: binder_alloc_buf, no vma\n", > alloc->pid); > @@ -723,9 +752,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc, > buffer->free = 1; > binder_insert_free_buffer(alloc, buffer); > alloc->free_async_space = alloc->buffer_size / 2; > - barrier(); > - alloc->vma = vma; > - alloc->vma_vm_mm = vma->vm_mm; > + binder_alloc_set_vma(alloc, vma); > mmgrab(alloc->vma_vm_mm); > > return 0; > @@ -754,10 +781,10 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc) > int buffers, page_count; > struct binder_buffer *buffer; > > - BUG_ON(alloc->vma); > - > buffers = 0; > mutex_lock(&alloc->mutex); > + BUG_ON(alloc->vma); > + > while ((n = rb_first(&alloc->allocated_buffers))) { > buffer = rb_entry(n, struct binder_buffer, rb_node); > > @@ -900,7 +927,7 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc) > */ > void binder_alloc_vma_close(struct binder_alloc *alloc) > { > - WRITE_ONCE(alloc->vma, NULL); > + binder_alloc_set_vma(alloc, NULL); > } > > /** > @@ -935,7 +962,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item, > > index = page - alloc->pages; > page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE; > - vma = alloc->vma; > + vma = binder_alloc_get_vma(alloc); > if (vma) { > if (!mmget_not_zero(alloc->vma_vm_mm)) > goto err_mmget; > -- > 2.18.0.1017.ga543ac7ca45-goog > > > > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel