From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91641C04AAD for ; Wed, 8 May 2019 14:45:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 72010216C4 for ; Wed, 8 May 2019 14:45:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728606AbfEHOpB (ORCPT ); Wed, 8 May 2019 10:45:01 -0400 Received: from mga11.intel.com ([192.55.52.93]:7358 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728245AbfEHOoo (ORCPT ); Wed, 8 May 2019 10:44:44 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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