linux-kernel - [PATCH v2 10/10] mm: hwpoison_user_mappings() try_to_unmap() with TTU

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Message-ID: <329c28ed-95df-9a2c-8893-b444d8a6d340@google.com>
Date:   Tue, 8 Jun 2021 21:30:00 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
cc:     Hugh Dickins <hughd@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>,
        Wang Yugui <wangyugui@...-tech.com>,
        Matthew Wilcox <willy@...radead.org>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        Alistair Popple <apopple@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>, Zi Yan <ziy@...dia.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Minchan Kim <minchan@...nel.org>, Jue Wang <juew@...gle.com>,
        Peter Xu <peterx@...hat.com>, Jan Kara <jack@...e.cz>,
        Shakeel Butt <shakeelb@...gle.com>,
        Oscar Salvador <osalvador@...e.de>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 10/10] mm: hwpoison_user_mappings() try_to_unmap() with
 TTU_SYNC

TTU_SYNC prevents an unlikely race, when try_to_unmap() returns shortly
before the page is accounted as unmapped.  It is unlikely to coincide
with hwpoisoning, but now that we have the flag, hwpoison_user_mappings()
would do well to use it.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---
Patch added since the v1 series was posted.

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

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b6806e446567..e16edefca523 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1060,7 +1060,7 @@ static int get_hwpoison_page(struct page *p, unsigned long flags,
 static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 				  int flags, struct page **hpagep)
 {
-	enum ttu_flags ttu = TTU_IGNORE_MLOCK;
+	enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_SYNC;
 	struct address_space *mapping;
 	LIST_HEAD(tokill);
 	bool unmap_success;
-- 
2.26.2