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Message-Id: <20210712060956.925981697@linuxfoundation.org>
Date: Mon, 12 Jul 2021 08:12:05 +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, Yang Shi <shy828301@...il.com>,
Miaohe Lin <linmiaohe@...wei.com>,
Alexey Dobriyan <adobriyan@...il.com>,
"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
Anshuman Khandual <anshuman.khandual@....com>,
David Hildenbrand <david@...hat.com>,
Hugh Dickins <hughd@...gle.com>,
Johannes Weiner <hannes@...xchg.org>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Matthew Wilcox <willy@...radead.org>,
Minchan Kim <minchan@...nel.org>,
Ralph Campbell <rcampbell@...dia.com>,
Rik van Riel <riel@...riel.com>,
Song Liu <songliubraving@...com>,
William Kucharski <william.kucharski@...cle.com>,
Zi Yan <ziy@...dia.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 565/593] mm/huge_memory.c: dont discard hugepage if other processes are mapping it
From: Miaohe Lin <linmiaohe@...wei.com>
[ Upstream commit babbbdd08af98a59089334eb3effbed5a7a0cf7f ]
If other processes are mapping any other subpages of the hugepage, i.e.
in pte-mapped thp case, page_mapcount() will return 1 incorrectly. Then
we would discard the page while other processes are still mapping it. Fix
it by using total_mapcount() which can tell whether other processes are
still mapping it.
Link: https://lkml.kernel.org/r/20210511134857.1581273-6-linmiaohe@huawei.com
Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called")
Reviewed-by: Yang Shi <shy828301@...il.com>
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@....com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Ralph Campbell <rcampbell@...dia.com>
Cc: Rik van Riel <riel@...riel.com>
Cc: Song Liu <songliubraving@...com>
Cc: William Kucharski <william.kucharski@...cle.com>
Cc: Zi Yan <ziy@...dia.com>
Cc: Mike Kravetz <mike.kravetz@...cle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
mm/huge_memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 07c664c47a4f..9fe622ff2fc4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1604,7 +1604,7 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
* If other processes are mapping this page, we couldn't discard
* the page unless they all do MADV_FREE so let's skip the page.
*/
- if (page_mapcount(page) != 1)
+ if (total_mapcount(page) != 1)
goto out;
if (!trylock_page(page))
--
2.30.2
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