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[23.128.96.37]) by mx.google.com with ESMTPS id q7-20020a170902dac700b001c44c0f8d96si23822883plx.251.2023.10.02.16.15.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 16:15:45 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20230601 header.b=nC2uPqKa; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by snail.vger.email (Postfix) with ESMTP id 17D8A80658EF; Mon, 2 Oct 2023 16:15:22 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237512AbjJBXPP (ORCPT + 99 others); Mon, 2 Oct 2023 19:15:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47562 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237247AbjJBXPJ (ORCPT ); Mon, 2 Oct 2023 19:15:09 -0400 Received: from mail-wr1-x436.google.com (mail-wr1-x436.google.com [IPv6:2a00:1450:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BBDBB8 for ; Mon, 2 Oct 2023 16:15:05 -0700 (PDT) Received: by mail-wr1-x436.google.com with SMTP id ffacd0b85a97d-3231d6504e1so326819f8f.2 for ; Mon, 02 Oct 2023 16:15:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696288504; x=1696893304; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=XG4wWkmLCo1BkRFV+SZ7pD22xcplU2FkjQ1ykcSCzlA=; b=nC2uPqKaHv+ZGud73irvViL69+e70oLHG/gE2GX5iioSIZDUkiEo98cvpWWRs1rQcv RfcE+uhXBrltGQtEpvz5V0Ax9Vnw2nM7lX0JoKEjmQrRg0E7591VUPJbjcstCmwofFqt q97vZQz+EFQTogxvoFm9ej8w8yjOU9/jGQiZ1G78g12HaTPIJCgnOYheji9YzxAH6hFv RkHR4NlcMwukPC/Z3H7sjjA4aD2VAyvsFFohdkgrlQg3CIGne/Vsx/wnikP4/SdmeoGJ otRHdMIZjHFKOPMVYH/oYiP7q01NGT3do9AuZPdKboGKT9dEGHO59C6F0sjg6a890Eh4 xhWA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696288504; x=1696893304; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=XG4wWkmLCo1BkRFV+SZ7pD22xcplU2FkjQ1ykcSCzlA=; b=NY/aBdgqAVPDE/MwiT/8tomrmf562qNV3S1OotbuNXsyRf/RtMZjeyFVkrmxicOq4h iB5QL4KHsOgsmyjCWIXF2RqOpcggBYhItPzMORWYeWX0aFabqjX4CP9sUZioLwv6+cz0 EVmdAr4ZYlJtsbjQlo3tqDPG0uUm1+tPH2oa2o0uBLrVI4mxNAuXrvlpwYjcj17jzOiG k3CHohqoewDsnQKOECjtHhDEjzpgHxbg40/unthwpdrFcacAa8+hihxC2B3aBeG+C+rx qjgkMvQRFPU/8Uwph1mWPnlGDUYxuuig2zrBMdZBn+AFoOi8bQVGzbo7L38X/rbxcU1U okcQ== X-Gm-Message-State: AOJu0Yx2+QcmQP1Eutl/q3VMefQ1wF0fF8Q9fSasj3cBaMMYNkGtbE4z ZdUwgoDLE6JzrNcSz4FlZvs= X-Received: by 2002:adf:ea8f:0:b0:320:1c6:628c with SMTP id s15-20020adfea8f000000b0032001c6628cmr12351480wrm.65.1696288503641; Mon, 02 Oct 2023 16:15:03 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id e31-20020a5d595f000000b0031fbbe347e1sm63860wri.65.2023.10.02.16.15.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 16:15:02 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Catalin Marinas , Will Deacon , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland Cc: Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Oleg Nesterov , Richard Cochran , Jason Gunthorpe , John Hubbard , Arnd Bergmann , Lorenzo Stoakes Subject: [PATCH v2 3/4] mm/gup: make failure to pin an error if FOLL_NOWAIT not specified Date: Tue, 3 Oct 2023 00:14:53 +0100 Message-ID: <2a42d96dd1e37163f90a0019a541163dafb7e4c3.1696288092.git.lstoakes@gmail.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Mon, 02 Oct 2023 16:15:22 -0700 (PDT) There really should be no circumstances under which a non-FOLL_NOWAIT GUP operation fails to return any pages, so make this an error and warn on it. To catch the trivial case, simply exit early if nr_pages == 0. This brings __get_user_pages_locked() in line with the behaviour of its nommu variant. Reviewed-by: Arnd Bergmann Signed-off-by: Lorenzo Stoakes --- mm/gup.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index b21b33d1787e..231711efa390 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1471,6 +1471,9 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, long ret, pages_done; bool must_unlock = false; + if (!nr_pages) + return 0; + /* * The internal caller expects GUP to manage the lock internally and the * lock must be released when this returns. @@ -1595,6 +1598,14 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, mmap_read_unlock(mm); *locked = 0; } + + /* + * Failing to pin anything implies something has gone wrong (except when + * FOLL_NOWAIT is specified). + */ + if (WARN_ON_ONCE(pages_done == 0 && !(flags & FOLL_NOWAIT))) + return -EFAULT; + return pages_done; } -- 2.42.0