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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CAF01CD3447 for ; Fri, 8 May 2026 12:19:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 154296B0158; Fri, 8 May 2026 08:19:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 12C416B0159; Fri, 8 May 2026 08:19:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0427D6B015A; Fri, 8 May 2026 08:19:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id E5EBD6B0158 for ; Fri, 8 May 2026 08:19:28 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 83C291C17D4 for ; Fri, 8 May 2026 12:19:28 +0000 (UTC) X-FDA: 84744158016.30.DB1FFA3 Received: from mail-lj1-f169.google.com (mail-lj1-f169.google.com [209.85.208.169]) by imf23.hostedemail.com (Postfix) with ESMTP id 9D668140002 for ; Fri, 8 May 2026 12:19:26 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=UDUuzOeq; spf=pass (imf23.hostedemail.com: domain of sozdayvek@gmail.com designates 209.85.208.169 as permitted sender) smtp.mailfrom=sozdayvek@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1778242766; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sPuuBoZsJsMQg4Ux+i6kMwWg7G2z365jWoV41M3Piz4=; b=W8GnW7QalvorgHkV5pu1sMmUPztlvKDgGlj3Sgg9KkvxoGCcwB0NHM8WoMaRVkzrmi7FZT RRm86qB/q+z6g4YlZFFpfaKZZvVZgee4zMOiDm8x/UCQlskUrP6OEZ4FhkCTFDPdt3+MaF hYo10I16EYt42KU+gph+w8fSOvnw0ks= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=UDUuzOeq; spf=pass (imf23.hostedemail.com: domain of sozdayvek@gmail.com designates 209.85.208.169 as permitted sender) smtp.mailfrom=sozdayvek@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1778242766; a=rsa-sha256; cv=none; b=cOrwWaXPHU5t+AdvE8fvO1CKCK5r2dil7wrJfI0BUGo7mMBPGAFz4z3XYVKqLoB4Xrd27k Jkb8ZsS3niZmXY8zkJjUFBImW7Y4wvNk94y+EW2QC0cbDjqpyvRD1efHeKhYXv10Q/zcq2 mbpQjbcieOoiFzhEdfy2StwpdaY+DBE= Received: by mail-lj1-f169.google.com with SMTP id 38308e7fff4ca-38ee0fe3bdeso2823061fa.2 for ; Fri, 08 May 2026 05:19:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1778242764; x=1778847564; darn=kvack.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=sPuuBoZsJsMQg4Ux+i6kMwWg7G2z365jWoV41M3Piz4=; b=UDUuzOeqoLKdtEFHzyBGdUCfVWSLB+HcYRxRWUIniA/se257BbJD2ec7ZUhfEvJVJk qF/eVkM0uXfx8wvJ3jLF6yqvy8BguOaM9TmqEG9w47ky2j1XQ4VgMKaur9Gs6HpaATx1 lyw0elbHRVXj5UIGelQaz6HJVbzMND0op827iBPqUw0Usd5MVQVj49sJW9PVj8Z8OzqM RWk5cEkvTuuylwZ0nssYnCKxID8OFOjTeBFFq/0uj46cYI2EJO+Jz0Sj+febAr6DXPK7 IJM2Jke4rn47Pd43+/i7IZBKD/K9z8Y+roHeuK6S7adg0Gbf0GX0G6swVbhpyqO0xPxb G6qA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778242764; x=1778847564; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=sPuuBoZsJsMQg4Ux+i6kMwWg7G2z365jWoV41M3Piz4=; b=tJVje+ug2dTSFVyNjQPm3c30wbmdESG39HIEjZoSaSSUqhTDKFT4/whqlbklD0FwU2 svUrTWmYTklK2uRNW1cFrnpPnjKY/mpjCMUPNu4Pli+sDNBdQO9dHhr2fpgwL0C7sq6q w026pgDtjQ0i6EIM+pT4+O11znQnIryeWee0SjfEGuSDFOLSNuI+kSQauuTdcmjqkN3d oA52yQzqVFTS50wgyjz8jIOAx9abJqAanMvsmqvNrauc06wJDoQJFo6U4kfEXQaeLH8m t3inmJtVXaiFIheygs/74R2/+FViHbPO5XyWMz/iaN3XQZt8xqrZul7aB9TI2oBlvJ7f DJPg== X-Forwarded-Encrypted: i=1; AFNElJ8LCiPew3V3/Wd0hnQ3kTflTh5lD5XCsKMjvWbue7vi15Geq/tuFnXmavs0kwOpI5bCPZ6U/iFWDg==@kvack.org X-Gm-Message-State: AOJu0Yx4k8hiM6hn+HETxBCHmnV/nG87t/5svYBBCXk6IQ0ZXuqEtPTH H8gum5FvZhTsK56wG/jIORRfCeVDz8VYx1WeJYJjeMrgbEC4ea9gY5jK X-Gm-Gg: Acq92OFWRMFVArq+CBcbdHB2ql8BAtWpBW3sEZeKgIW1Ct/rqPt6MoMDpvZjIEyj4qU 85tRYoTzAaZVS5Z/Z9wVk1ML4O2gWBJuLljjwvk3OKkduXQHi/pHc44ykDQQV62qVGNy6eSTjkv 1UGkcA2hqs6R9oPeQezk4b57vUI0PQsWYT1VHHPt9iw/szON2weqiX13SHQTDJvxDO9vzEx1WjM IaZSu0BAQb6WcApVTzwBLFrjfdtxg5IRktV25Pp9hGr5LxUNNj8L5T5GKwZOGSSBiP8i2a3lgQ9 kz1iVsOI9zOMsbx9Bg5+tWRCyhOSpdndF0wU+RPtwwWNyKL3qR9AfIJ/QGRQ2vLRTBsO0vbsafa LTv2bMmUxAc5MNwGZPDp0Te1xftb6WOQLZ4alABoKf9YtaFa4Jpmg+bkncuYQzWFHRV0t0yk+MX Rbz3FlnkNfJGqEmq+BuS6dpqJjXbjY3pPQbmhC2DgDpQtm0T8= X-Received: by 2002:a05:6512:3a93:b0:5a8:7396:63e3 with SMTP id 2adb3069b0e04-5a887ce5f21mr1706229e87.5.1778242764182; Fri, 08 May 2026 05:19:24 -0700 (PDT) Received: from localhost.localdomain ([144.124.192.245]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5a8a95652acsm474206e87.56.2026.05.08.05.19.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 May 2026 05:19:23 -0700 (PDT) From: Stepan Ionichev To: david@kernel.org Cc: akpm@linux-foundation.org, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Stepan Ionichev Subject: Re: [PATCH] mm/gup: tolerate NULL unlocked in fixup_user_fault() Date: Fri, 8 May 2026 16:18:49 +0500 Message-Id: <20260508111849.10379-1-sozdayvek@gmail.com> X-Mailer: git-send-email 2.33.0.windows.2 In-Reply-To: References: <20260507083050.416-1-sozdayvek@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: eqf53aj8q7dhakoocw36zowhwo3jrajd X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 9D668140002 X-Rspam-User: X-HE-Tag: 1778242766-856053 X-HE-Meta: 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 x7m4ePmi 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 08 May 2026, David Hildenbrand wrote: > That would be completely broken. We must not drop the mmap lock unless > FAULT_FLAG_ALLOW_RETRY was set. Returning VM_FAULT_COMPLETED/VM_FAULT_RETRY > would mean that we did that. Broken. > > And the function documents "If NULL, the caller must guarantee that fault_flags > does not contain FAULT_FLAG_ALLOW_RETRY." You're right -- the contract is already enforced by the surrounding code and documented at the function. Defensive guards against an impossible scenario would just hide future real bugs. Please drop this patch. Thanks for taking the time to explain. Stepan