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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B6D7C433F5 for ; Mon, 3 Oct 2022 21:36:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229731AbiJCVgW (ORCPT ); Mon, 3 Oct 2022 17:36:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229733AbiJCVf5 (ORCPT ); Mon, 3 Oct 2022 17:35:57 -0400 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12F6263C8 for ; Mon, 3 Oct 2022 14:32:34 -0700 (PDT) Received: by mail-pl1-x62a.google.com with SMTP id f23so10796671plr.6 for ; Mon, 03 Oct 2022 14:32:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:from:to:cc:subject:date; bh=ZuRCUl6HMVxBq0xSk9jSUx9iN/xsLc64vNYxQtVKrJE=; b=JjwHslh0LG2aAfS0Fb4RaGPpmGCNi58yusVxfb7nSqOwnv8rRdfK0rlN/PCcJfb27I /1ahyFCKK8F4kmI7XvKqu5gpjzaJEt2pzykZl4FxKOp8J2aMvu6qXtKIZg/MYg8jzWpR YFpRZB17dBQl7krFq6+QJhSvu074CoNDgFkAQaQ9s5moBZenGl9UPxoZBns5rq3M8S9T JRnWF1hSm9wewHqJF4uS1GoWg9BsHoSWO26EuVj5hTmyqlsaI/Wh87Rj1xQ1XqGJzIYU sbYYfTAuk15fQXlI+F51KMyMPVCwuavNy1zsBU8r6mMjernlh+U0xqstpmfXC3nfE8xd ljVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:x-gm-message-state:from:to:cc :subject:date; bh=ZuRCUl6HMVxBq0xSk9jSUx9iN/xsLc64vNYxQtVKrJE=; b=je9B8XnbmloroIbuwPafBsnmVC3TqUo5ZlvIPCO/0puaymjK+nBCw/LpkrQxndqypG Qkr0NULxL8RMwZytwd4hbLtfMguVPfjjQkcqsmjmvriMMvC9ihnsuJocacEbQ7ildPm0 EdkbLvzs1keCBtEqeYB2PksbF3tC1xcjtzk1IiVTNnGXRFWMr5NjsejIfXt4El4hLNpq mBdzVnbCD7VJfSlBVl5jHNalTPhwl+zirmLmFKJq2oh/dGHTpQ9R/31OJ8adNsZPgm2X vDtcIDfQ7mPDI/VK3g6TCO8zYw+/WG0Xv5x/NURvc5omrYixgVUAjLFWNFMxP0QXD+cK sg+Q== X-Gm-Message-State: ACrzQf1DW6YPAfQCN+v5mOhh3AiAPhTkEr5NA4zPNdg8kTShvF4zf9hK H1dLBmnZSD2mi2+mzrdkHq171hO11FJdMN0I X-Google-Smtp-Source: AMsMyM5tgwjt2ZzRUzY5eF7WQIxz+cdMiLlXU+UEX28a9b6I9SHSqdW55ZCGbNrsIq8zUEg3I2kwjg== X-Received: by 2002:a17:902:8ec5:b0:179:ffdc:ee4d with SMTP id x5-20020a1709028ec500b00179ffdcee4dmr24606007plo.124.1664832753300; Mon, 03 Oct 2022 14:32:33 -0700 (PDT) Received: from smtpclient.apple ([66.170.99.2]) by smtp.gmail.com with ESMTPSA id e12-20020a170902d38c00b0017b5e1f486asm7613440pld.211.2022.10.03.14.32.32 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Oct 2022 14:32:32 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Re: [PATCH 1/3] mm/hugetlb: Fix race condition of uffd missing/minor handling From: Nadav Amit In-Reply-To: Date: Mon, 3 Oct 2022 14:32:31 -0700 Cc: LKML , Linux MM , Andrea Arcangeli , Mike Rapoport , David Hildenbrand , Andrew Morton , Axel Rasmussen , Mike Kravetz Content-Transfer-Encoding: quoted-printable Message-Id: <568C0BF2-28B9-438C-93D2-19130FAA3364@gmail.com> References: <20221003155630.469263-1-peterx@redhat.com> <20221003155630.469263-2-peterx@redhat.com> To: Peter Xu X-Mailer: Apple Mail (2.3696.120.41.1.1) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Oct 3, 2022, at 2:16 PM, Peter Xu wrote: > On Mon, Oct 03, 2022 at 02:00:36PM -0700, Nadav Amit wrote: >> On Oct 3, 2022, at 8:56 AM, Peter Xu wrote: >>=20 >>> + */ >>> + if (hugetlb_pte_stable(h, mm, ptep, old_pte)) >>> + ret =3D hugetlb_handle_userfault( >>> + vma, mapping, idx, flags, haddr, >>> + address, VM_UFFD_MISSING); >>> + else >>> + /* Retry the fault */ >>> + ret =3D 0; >>=20 >> Might be unrelated, but at least for the sake of consistency if not >> potential GUP issues, don=E2=80=99t you want to return VM_FAULT_RETRY = ? >=20 > VM_FAULT_RETRY implies releasing of mmap sem, while we didn't? Of course. My bad.