[patch 06/15] mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy_page() fails

[patch 06/15] mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy_page() fails

[akpm]

From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Subject: mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy_page() fails

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@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining")
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com>
Cc: "Chen, Jerry T" <jerry.t.chen@intel.com>
Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@intel.com>
Cc: <stable@vger.kernel.org>	[4.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- a/mm/memory-failure.c~mm-soft-offline-return-ebusy-if-set_hwpoison_free_buddy_page-fails
+++ a/mm/memory-failure.c
@@ -1730,6 +1730,8 @@ 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;
_