[PATCH 5.1 13/55] mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy_page() fails

[Greg Kroah-Hartman]

From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>

commit b38e5962f8ed0d2a2b28a887fc2221f7f41db119 upstream.

The pass/fail of soft offline should be judged by checking whether the
raw error page was finally contained or not (i.e.  the result of
set_hwpoison_free_buddy_page()), but current code do not work like
that.  It might lead us to misjudge the test result when
set_hwpoison_free_buddy_page() fails.

Without this fix, there are cases where madvise(MADV_SOFT_OFFLINE) may
not offline the original page and will not return an error.

Link: http://lkml.kernel.org/r/1560154686-18497-2-git-send-email-n-horiguchi@xxxxxxxxxxxxx
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining")
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Xishi Qiu <xishi.qiuxishi@xxxxxxxxxxxxxxx>
Cc: "Chen, Jerry T" <jerry.t.chen@xxxxxxxxx>
Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[4.19+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 mm/memory-failure.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1733,6 +1733,8 @@ static int soft_offline_huge_page(struct
 		if (!ret) {
 			if (set_hwpoison_free_buddy_page(page))
 				num_poisoned_pages_inc();
+			else
+				ret = -EBUSY;
 		}
 	}
 	return ret;