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From:   Miaohe Lin <linmiaohe@huawei.com>
To:     <akpm@linux-foundation.org>, <naoya.horiguchi@nec.com>
CC:     <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <linmiaohe@huawei.com>
Subject: [PATCH v2 5/6] mm, hwpoison: kill procs if unmap fails
Date:   Tue, 23 Aug 2022 11:23:45 +0800
Message-ID: <20220823032346.4260-6-linmiaohe@huawei.com>
In-Reply-To: <20220823032346.4260-1-linmiaohe@huawei.com>
References: <20220823032346.4260-1-linmiaohe@huawei.com>
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If try_to_unmap() fails, the hwpoisoned page still resides in the address
space of some processes. We should kill these processes or the hwpoisoned
page might be consumed later. collect_procs() is always called to collect
relevant processes now so they can be killed later if unmap fails.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
 mm/memory-failure.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index f8262f577baf..c2910f9af1d4 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1397,7 +1397,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	struct address_space *mapping;
 	LIST_HEAD(tokill);
 	bool unmap_success;
-	int kill = 1, forcekill;
+	int forcekill;
 	bool mlocked = PageMlocked(hpage);
 
 	/*
@@ -1438,7 +1438,6 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 		if (page_mkclean(hpage)) {
 			SetPageDirty(hpage);
 		} else {
-			kill = 0;
 			ttu |= TTU_IGNORE_HWPOISON;
 			pr_info("%#lx: corrupted page was clean: dropped without side effects\n",
 				pfn);
@@ -1449,12 +1448,8 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	 * First collect all the processes that have the page
 	 * mapped in dirty form.  This has to be done before try_to_unmap,
 	 * because ttu takes the rmap data structures down.
-	 *
-	 * Error handling: We ignore errors here because
-	 * there's nothing that can be done.
 	 */
-	if (kill)
-		collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
+	collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
 
 	if (PageHuge(hpage) && !PageAnon(hpage)) {
 		/*
@@ -1496,7 +1491,8 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	 * use a more force-full uncatchable kill to prevent
 	 * any accesses to the poisoned memory.
 	 */
-	forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL);
+	forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL) ||
+		    !unmap_success;
 	kill_procs(&tokill, forcekill, !unmap_success, pfn, flags);
 
 	return unmap_success;
-- 
2.23.0