On Mon, 28 Aug 2017, Mel Gorman wrote:
> Wendy Wang reported off-list that a RAS HWPOISON-SOFT test case failed and
> bisected it to the commit 479f854a207c ("mm, page_alloc: defer debugging
> checks of pages allocated from the PCP"). The problem is that a page that
> was poisoned with madvise() is reused. The commit removed a check that
> would trigger if DEBUG_VM was enabled but re-enabling the check only
> fixes the problem as a side-effect by printing a bad_page warning and
> recovering.
>
> The root of the problem is that a madvise() can leave a poisoned on
> the per-cpu list. This patch drains all per-cpu lists after pages are
> poisoned so that they will not be reused. Wendy reports that the test case
> in question passes with this patch applied. While this could be done in
> a targeted fashion, it is over-complicated for such a rare operation.
>
> Fixes: 479f854a207c ("mm, page_alloc: defer debugging checks of pages
> allocated from the PCP")
> Reported-and-tested-by: Wang, Wendy <[email protected]>
> Cc: [email protected]
> Signed-off-by: Mel Gorman <[email protected]>
Acked-by: David Rientjes <[email protected]>
