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[192.55.52.88]) by mx.google.com with ESMTPS id g13si12322802pgs.161.2019.05.08.07.44.43 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 May 2019 07:44:44 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of kirill.shutemov@linux.intel.com designates 192.55.52.88 as permitted sender) client-ip=192.55.52.88; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of kirill.shutemov@linux.intel.com designates 192.55.52.88 as permitted sender) smtp.mailfrom=kirill.shutemov@linux.intel.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 May 2019 07:44:43 -0700 X-ExtLoop1: 1 Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga004.fm.intel.com with ESMTP; 08 May 2019 07:44:39 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id B90ABA50; Wed, 8 May 2019 17:44:29 +0300 (EEST) From: "Kirill A. Shutemov" To: Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Peter Zijlstra , Andy Lutomirski , David Howells Cc: Kees Cook , Dave Hansen , Kai Huang , Jacob Pan , Alison Schofield , linux-mm@kvack.org, kvm@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCH, RFC 21/62] mm/rmap: Clear vma->anon_vma on unlink_anon_vmas() Date: Wed, 8 May 2019 17:43:41 +0300 Message-Id: <20190508144422.13171-22-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190508144422.13171-1-kirill.shutemov@linux.intel.com> References: <20190508144422.13171-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: If all pages in the VMA got unmapped there's no reason to link it into original anon VMA hierarchy: it cannot possibly share any pages with other VMA. Set vma->anon_vma to NULL on unlink_anon_vmas(). With the change VMA can be reused. The new anon VMA will be allocated on the first fault. Signed-off-by: Kirill A. Shutemov --- mm/rmap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/rmap.c b/mm/rmap.c index b30c7c71d1d9..4ec2aee7baa3 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -400,8 +400,10 @@ void unlink_anon_vmas(struct vm_area_struct *vma) list_del(&avc->same_vma); anon_vma_chain_free(avc); } - if (vma->anon_vma) + if (vma->anon_vma) { vma->anon_vma->degree--; + vma->anon_vma = NULL; + } unlock_anon_vma_root(root); /* -- 2.20.1