Re: [PATCH 3/3] Convert a few VM_BUG_ON callers to VM_BUG_ON_VMA

Naoya Horiguchi
2014-08-29T19:17:37Z

On Fri, Aug 29, 2014 at 10:54:19AM -0400, Sasha Levin wrote:
> Trivially convert a few VM_BUG_ON calls to VM_BUG_ON_VMA to extract
> more information when they trigger.
>
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> ---
...
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 3e8491c..5fbd0fe 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
...
> @@ -897,7 +897,7 @@ void page_move_anon_rmap(struct page *page,
> struct anon_vma *anon_vma = vma->anon_vma;
>
> VM_BUG_ON_PAGE(!PageLocked(page), page);
> - VM_BUG_ON(!anon_vma);
> + VM_BUG_ON_VMA(!anon_vma, vma);

> VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);

This line contains both of vma and page.
But I'm not sure that introducing another macro like VM_BUG_ON_PAGE_AND_VMA()
is worth doing. So it's ok for me to keep it untouched.

>
> anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
> @@ -1024,7 +1024,7 @@ void do_page_add_anon_rmap(struct page *page,
> void page_add_new_anon_rmap(struct page *page,
> struct vm_area_struct *vma, unsigned long address)
> {
> - VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
> + VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
> SetPageSwapBacked(page);
> atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
> if (PageTransHuge(page))
> @@ -1666,7 +1666,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
> * structure at mapping cannot be freed and reused yet,
> * so we can safely take mapping->i_mmap_mutex.
> */
> - VM_BUG_ON(!PageLocked(page));
> + VM_BUG_ON_PAGE(!PageLocked(page), page);

This is not the replacement with VM_BUG_ON_VMA(), but it's fine :)

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Thanks,
Naoya Horiguchi