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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 2AEDDC433E0 for ; Fri, 15 Jan 2021 17:12:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 028642333E for ; Fri, 15 Jan 2021 17:12:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733290AbhAORLV (ORCPT ); Fri, 15 Jan 2021 12:11:21 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:57219 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733221AbhAORLM (ORCPT ); Fri, 15 Jan 2021 12:11:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610730585; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yBkQRG2pL7J64zZlZOQIc2dhhUBB5j7m8vruAB1Id6o=; b=Trm0kIuWJ6zgIp4I0TwYTcAuFeUc5BfNCHMHLZu1OjNgJzKn1Fxeg/qK7x0Vp/PRuPBV2S bHrAzrAVNlH/okCXfmbBDMaTDh9s8eSP+DsogZJtmeDzz49D6iz4fifkRfrvVSfGyRLUGw V+ZGxGopdSdhvoK2Tgd1jb0wtmFN7QE= Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-464-XljvGerZNEyo8Wzj26cZ2g-1; Fri, 15 Jan 2021 12:09:44 -0500 X-MC-Unique: XljvGerZNEyo8Wzj26cZ2g-1 Received: by mail-qk1-f200.google.com with SMTP id 189so8627205qko.1 for ; Fri, 15 Jan 2021 09:09:44 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=yBkQRG2pL7J64zZlZOQIc2dhhUBB5j7m8vruAB1Id6o=; b=Ahx3W4NYRJ4hidJn1K9e16nW65N9vjFCXN0Uj55t9rrWQaEsxhhQvY0GnOacWxg2Vr q5A/sGE66oH2qg+fgfYndbvmmQiDp6QkAcpvk20IC3DFMFDoCYzyMrOEO4GKur2MheEC 8p1WiyF1LzuwqGNAX3SFHB4pQPYb+wC4xgxdyXZCMO5h3XRpqWyn1Q/D24htwZ8ayHSW hv77vv9j9JpyBFJd3/QyeD/IrXo6JJ+KHWY2p1rwcDus6U2CVF+LTbzSJLzr3brYss5Y 8JYxuXkmehMNHjmJklL7fndMCHgLXOwVHNbJtRk58Tsr10zjXxxHDuQaoGT7ahgpRDU1 7q3A== X-Gm-Message-State: AOAM531gCUEP8BxfAzcldpT59brIUuHAlUfk1b62hna1P/TL4gX0BBBU eFvf/fyvuBgO5lky4BjTjKTdPTFmbWn/HPDd+glk/IPpLK4z65QMuJivac4pQJcNI6xu/H2cXK8 VZy/rzRy5wU3CiSIV+qOcTrbfK3WvtX8egkjhiaSUuQg/BRsP0/kzBD6/YEkWBOsrig7bNw7o5A == X-Received: by 2002:a05:620a:1264:: with SMTP id b4mr13698550qkl.187.1610730583651; Fri, 15 Jan 2021 09:09:43 -0800 (PST) X-Google-Smtp-Source: ABdhPJya4OiwdJGAuCczPlqaSBaKxxbyDX4PGAfQreU5Kr2CdzlXJm35YPbgKxKn0g+KWI8OS78AjA== X-Received: by 2002:a05:620a:1264:: with SMTP id b4mr13698504qkl.187.1610730583353; Fri, 15 Jan 2021 09:09:43 -0800 (PST) Received: from localhost.localdomain ([142.126.83.202]) by smtp.gmail.com with ESMTPSA id d123sm5187840qke.95.2021.01.15.09.09.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Jan 2021 09:09:42 -0800 (PST) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Mike Rapoport , Mike Kravetz , peterx@redhat.com, Jerome Glisse , "Kirill A . Shutemov" , Hugh Dickins , Axel Rasmussen , Matthew Wilcox , Andrew Morton , Andrea Arcangeli , Nadav Amit Subject: [PATCH RFC 17/30] shmem/userfaultfd: Pass over uffd-wp special swap pte when fork() Date: Fri, 15 Jan 2021 12:08:54 -0500 Message-Id: <20210115170907.24498-18-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210115170907.24498-1-peterx@redhat.com> References: <20210115170907.24498-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It should be handled similarly like other uffd-wp wr-protected ptes: we should pass it over when the dst_vma has VM_UFFD_WP armed, otherwise drop it. Signed-off-by: Peter Xu --- mm/memory.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index f87b5a8a098e..59d56f57ba2c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -703,8 +703,21 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, unsigned long vm_flags = dst_vma->vm_flags; pte_t pte = *src_pte; struct page *page; - swp_entry_t entry = pte_to_swp_entry(pte); + swp_entry_t entry; + + if (unlikely(is_swap_special_pte(pte))) { + /* + * uffd-wp special swap pte is the only possibility for now. + * If dst vma is registered with uffd-wp, copy it over. + * Otherwise, ignore this pte as if it's a none pte would work. + */ + WARN_ON_ONCE(!pte_swp_uffd_wp_special(pte)); + if (userfaultfd_wp(dst_vma)) + set_pte_at(dst_mm, addr, dst_pte, pte); + return 0; + } + entry = pte_to_swp_entry(pte); if (likely(!non_swap_entry(entry))) { if (swap_duplicate(entry) < 0) return entry.val; -- 2.26.2