Hi Andrew, On Wed, Dec 18, 2013 at 05:04:29PM -0800, Andrew Morton wrote: >On Thu, 19 Dec 2013 09:58:05 +0900 Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> 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 <liwanp@xxxxxxxxxxxxxxxxxx> 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. I will add this check and explanation to the callee rmap_one hook of rmap_walk_control and send another version of the patch. ;-) Regards, Wanpeng Li -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>