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From: Miaohe Lin <linmiaohe@huawei.com>
To: <akpm@linux-foundation.org>
Cc: <ziy@nvidia.com>, <william.kucharski@oracle.com>,
	<willy@infradead.org>, <yang.shi@linux.alibaba.com>,
	<aneesh.kumar@linux.ibm.com>, <rcampbell@nvidia.com>,
	<songliubraving@fb.com>, <kirill.shutemov@linux.intel.com>,
	<riel@surriel.com>, <hannes@cmpxchg.org>, <minchan@kernel.org>,
	<hughd@google.com>, <adobriyan@gmail.com>,
	<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
	<linux-fsdevel@vger.kernel.org>, <linmiaohe@huawei.com>
Subject: [PATCH v3 5/5] mm/huge_memory.c: don't discard hugepage if other processes are mapping it
Date: Tue, 11 May 2021 21:48:57 +0800	[thread overview]
Message-ID: <20210511134857.1581273-6-linmiaohe@huawei.com> (raw)
In-Reply-To: <20210511134857.1581273-1-linmiaohe@huawei.com>

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.

Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called")
Reviewed-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 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 b8e67332806f..24647fe076b8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1610,7 +1610,7 @@ 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))
-- 
2.23.0


      parent reply	other threads:[~2021-05-11 13:49 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11 13:48 [PATCH v3 0/5] Cleanup and fixup for huge_memory Miaohe Lin
2021-05-11 13:48 ` [PATCH v3 1/5] mm/huge_memory.c: remove dedicated macro HPAGE_CACHE_INDEX_MASK Miaohe Lin
2021-05-11 13:48 ` [PATCH v3 2/5] mm/huge_memory.c: use page->deferred_list Miaohe Lin
2021-05-11 23:03   ` Matthew Wilcox
2021-05-12  2:02     ` Miaohe Lin
2021-05-11 13:48 ` [PATCH v3 3/5] mm/huge_memory.c: add missing read-only THP checking in transparent_hugepage_enabled() Miaohe Lin
2021-05-13 21:30   ` Yang Shi
2021-05-14  1:53     ` Miaohe Lin
2021-05-11 13:48 ` [PATCH v3 4/5] mm/huge_memory.c: remove unnecessary tlb_remove_page_size() for huge zero pmd Miaohe Lin
2021-05-11 13:48 ` Miaohe Lin [this message]

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