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Wed, 10 Nov 2021 02:55:24 -0800 (PST) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.251]) by smtp.gmail.com with ESMTPSA id v38sm5865829pgl.38.2021.11.10.02.55.18 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 10 Nov 2021 02:55:24 -0800 (PST) From: Qi Zheng To: akpm@linux-foundation.org, tglx@linutronix.de, kirill.shutemov@linux.intel.com, mika.penttila@nextfour.com, david@redhat.com, jgg@nvidia.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, songmuchun@bytedance.com, zhouchengming@bytedance.com, Qi Zheng Subject: [PATCH v3 08/15] mm/pte_ref: initialize the refcount of the withdrawn PTE page table page Date: Wed, 10 Nov 2021 18:54:21 +0800 Message-Id: <20211110105428.32458-9-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20211110105428.32458-1-zhengqi.arch@bytedance.com> References: <20211110105428.32458-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7E85660019BC X-Stat-Signature: ah39ydumruxtof1wy53gfbbbwsqxz7zy Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=VOdIGEoo; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf14.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.215.173 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com X-HE-Tag: 1636541726-425923 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When we split the PMD-mapped THP to the PTE-mapped THP, we should initialize the refcount of the withdrawn PTE page table page to HPAGE_PMD_NR, which ensures that we can release the PTE page table page when it is free(the refcount is 0). Signed-off-by: Qi Zheng --- mm/pgtable-generic.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index 4e640baf9794..523053e09dfa 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -186,6 +186,7 @@ pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp) struct page, lru); if (pmd_huge_pte(mm, pmdp)) list_del(&pgtable->lru); + pte_ref_init(pgtable, pmdp, HPAGE_PMD_NR); return pgtable; } #endif