On Thu, 19 Dec 2013 09:58:05 +0900 Joonsoo Kim <iamjoonsoo....@lge.com> wrote:
> On Wed, Dec 18, 2013 at 04:28:58PM -0800, Andrew Morton wrote:
> > On Thu, 19 Dec 2013 08:16:35 +0800 Wanpeng Li <liw...@linux.vnet.ibm.com>
> > wrote:
> >
> > > page_get_anon_vma() called in page_referenced_anon() will lock and
> > > increase the refcount of anon_vma, page won't be locked for anonymous
> > > page. This patch fix it by skip check anonymous page locked.
> > >
> > > [ 588.698828] kernel BUG at mm/rmap.c:1663!
> >
> > Why is all this suddenly happening. Did we change something, or did a
> > new test get added to trinity?
>
> It is my fault.
> I should remove this VM_BUG_ON() since rmap_walk() can be called
> without holding PageLock() in this case.
>
> I think that adding VM_BUG_ON() to each rmap_walk calllers is better
> than this patch, because, now, rmap_walk() is called by many places and
> each places has different contexts.
I don't think that putting the assertion into the caller makes a lot of
sense, particularly if that code just did a lock_page()! If a *callee*
needs PageLocked() then that callee should assert that the page is
locked. So
VM_BUG_ON(!PageLocked(page));
means "this code requires that the page be locked". And if that code
requires PageLocked(), there must be reasons for this. Let's also
include an explanation of those reasons.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
