mm, madvise: ensure poisoned pages are removed from per-cpu lists
Wendy Wang reported off-list that a RAS HWPOISON-SOFT test case failed and bisected it to the commit 479f854a ("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 an madvise() can leave a poisoned page 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. Link: http://lkml.kernel.org/r/20170828133414.7qro57jbepdcyz5x@techsingularity.net Fixes: 479f854a ("mm, page_alloc: defer debugging checks of pages allocated from the PCP") Signed-off-by: NMel Gorman <mgorman@techsingularity.net> Reported-by: NWang, Wendy <wendy.wang@intel.com> Tested-by: NWang, Wendy <wendy.wang@intel.com> Acked-by: NDavid Rientjes <rientjes@google.com> Acked-by: NVlastimil Babka <vbabka@suse.cz> Cc: "Hansen, Dave" <dave.hansen@intel.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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