linux-kernel - [PATCH 4.19 36/72] mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy

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Date:   Tue,  2 Jul 2019 10:01:37 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Oscar Salvador <osalvador@...e.de>,
        Michal Hocko <mhocko@...nel.org>,
        Xishi Qiu <xishi.qiuxishi@...baba-inc.com>,
        "Chen, Jerry T" <jerry.t.chen@...el.com>,
        "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.19 36/72] mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy_page() fails

From: Naoya Horiguchi <n-horiguchi@...jp.nec.com>

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@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining")
Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Xishi Qiu <xishi.qiuxishi@...baba-inc.com>
Cc: "Chen, Jerry T" <jerry.t.chen@...el.com>
Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>
Cc: <stable@...r.kernel.org>	[4.19+]
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1731,6 +1731,8 @@ 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;