On Tue 05-12-17 16:16:35, Ben Hutchings wrote:
On Wed, 2017-11-22 at 13:09 +0100, Michal Hocko wrote:
From: Yang Shi yang.shi@linaro.org
commit f86e4271978bd93db466d6a95dad4b0fdcdb04f6 upstream.
Per the discussion with Joonsoo Kim [1], we need check the return value of lookup_page_ext() for all call sites since it might return NULL in some cases, although it is unlikely, i.e. memory hotplug.
Tested with ltp with "page_owner=0".
[...]
--- a/mm/debug-pagealloc.c +++ b/mm/debug-pagealloc.c @@ -34,6 +34,8 @@ static inline void set_page_poison(struct page *page) struct page_ext *page_ext; page_ext = lookup_page_ext(page);
- if (page_ext)
return;This, and the other checks added to debug-pagealloc.c, are reversed. (This is specific to the 4.4 backport - in the upstream version these functions are in mm/page_poison.c and were patched correctly.)
Yes, I've sent a fixup and Greg has queued it up as 0208fabf7256245125fbabf03207a0da4000ea2d