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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 5D5FEC433E0 for ; Wed, 24 Feb 2021 20:06:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1840D64F1B for ; Wed, 24 Feb 2021 20:06:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234718AbhBXUGj (ORCPT ); Wed, 24 Feb 2021 15:06:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:55460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235316AbhBXUFz (ORCPT ); Wed, 24 Feb 2021 15:05:55 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7E34164F36; Wed, 24 Feb 2021 20:04:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614197090; bh=o5B2UwUoJBuubQ9hFq7S1qGARKUxOP/DrAwHAuIUB9s=; h=Date:From:To:Subject:In-Reply-To:From; b=oCvZTMNtDzZZMa6A+QSEMsvYKBuAbdcR1ITA0W++v4hXJfLUtlxY67kEX9CQJ29xd LKR3CgnGwgnAuNU5Y/R1kOoUaoojpydwZXr/Fearnp4OlAPuEAIPQiTKvxDgJLExFQ pNngKXLa4/hBrIJxzsKHa2T/1vkfJ+VBzBo4EsqQ= Date: Wed, 24 Feb 2021 12:04:49 -0800 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, bgeffon@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, lixinhai.lxh@gmail.com, lokeshgidra@google.com, minchan@kernel.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 082/173] mm: rmap: explicitly reset vma->anon_vma in unlink_anon_vmas() Message-ID: <20210224200449.hkU5GTEiH%akpm@linux-foundation.org> In-Reply-To: <20210224115824.1e289a6895087f10c41dd8d6@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Li Xinhai Subject: mm: rmap: explicitly reset vma->anon_vma in unlink_anon_vmas() In case the vma will continue to be used after unlink its relevant anon_vma, we need to reset the vma->anon_vma pointer to NULL. So, later when fault happen within this vma again, a new anon_vma will be prepared. By this way, the vma will only be checked for reverse mapping of pages which been fault in after the unlink_anon_vmas call. Currently, the mremap with MREMAP_DONTUNMAP scenario will continue use the vma after moved its page table entries to a new vma. For other scenarios, the vma itself will be freed after call unlink_anon_vmas. Link: https://lkml.kernel.org/r/20210119075126.3513154-1-lixinhai.lxh@gmail.com Signed-off-by: Li Xinhai Cc: Andrea Arcangeli Cc: Brian Geffon Cc: Kirill A. Shutemov Cc: Lokesh Gidra Cc: Minchan Kim Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/rmap.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/mm/rmap.c~mm-rmap-explicitly-reset-vma-anon_vma-in-unlink_anon_vmas +++ a/mm/rmap.c @@ -413,8 +413,15 @@ void unlink_anon_vmas(struct vm_area_str list_del(&avc->same_vma); anon_vma_chain_free(avc); } - if (vma->anon_vma) + if (vma->anon_vma) { vma->anon_vma->degree--; + + /* + * vma would still be needed after unlink, and anon_vma will be prepared + * when handle fault. + */ + vma->anon_vma = NULL; + } unlock_anon_vma_root(root); /* _