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[2604:1380:45e3:2400::1]) by mx.google.com with ESMTPS id 14-20020a63154e000000b005ce0160b1d3si2058775pgv.851.2024.01.18.13.59.59 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jan 2024 13:59:59 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-30588-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1; Authentication-Results: mx.google.com; dkim=pass header.i=@linux-foundation.org header.s=korg header.b=iS73GSEO; arc=pass (i=1 dkim=pass dkdomain=linux-foundation.org); spf=pass (google.com: domain of linux-kernel+bounces-30588-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-30588-linux.lists.archive=gmail.com@vger.kernel.org" Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sv.mirrors.kernel.org (Postfix) with ESMTPS id 66D852897EF for ; Thu, 18 Jan 2024 21:59:59 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A391F31A79; Thu, 18 Jan 2024 21:59:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="iS73GSEO" Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D84C2E848; Thu, 18 Jan 2024 21:59:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705615186; cv=none; b=E/6LFwSfrmKWp6c5JgaFvwfyadLYOeZV4LAsJ5a/wTckbNK+qq70WlAdBibWr/90RBtkHzilPp/FscJ/VcgtCr8C4q/i26aqWwE4LLjSuo8oR/+G+xi1Khc5IN1mlr4wu/wbQxbdEiBezp69kwwVQE9m1XPDtuV4UAIzb58Pw8M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705615186; c=relaxed/simple; bh=mSqSrX7G5ZUR4Mnn7J6yXV/zLXQD7Pr34tqNmgcTqBE=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=Oei4WUAL5zP6NVRZNpxPJEbH7LfsTchq0pXXGtRTcUehgrnaOCdPxYg6yXpCHpbjokPgCz9YZtigi8rsl5sn7MrSc478uhRvxtoVgl+Of4eVOx9nvOpS70w8T900oKGK3hATb/x5FSyf53mMHPgmra6e8z1tbUJxpY1wGi+qZU4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=iS73GSEO; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21B20C433F1; Thu, 18 Jan 2024 21:59:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1705615186; bh=mSqSrX7G5ZUR4Mnn7J6yXV/zLXQD7Pr34tqNmgcTqBE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=iS73GSEOVBGj8srjQKqXxORp8aFyAUqqJrJieP4bSt+uz80QDAlDkQr+C+dTHzVec n1WAekPJ/ujc0WiehjMBtxpcA0iQNxVNFcC4gKAwjPVZjQSkEeE6Xtwo2KhHRoAyB3 P0b0lol4VrgCn1uKfPTgI6ZtCRcORPz0UHuoEoIc= Date: Thu, 18 Jan 2024 13:59:41 -0800 From: Andrew Morton To: Lokesh Gidra Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, selinux@vger.kernel.org, surenb@google.com, kernel-team@android.com, aarcange@redhat.com, peterx@redhat.com, david@redhat.com, axelrasmussen@google.com, bgeffon@google.com, willy@infradead.org, jannh@google.com, kaleshsingh@google.com, ngeoffray@google.com Subject: Re: [PATCH] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb Message-Id: <20240118135941.c7795d52881f486aa21aeea8@linux-foundation.org> In-Reply-To: <20240117223729.1444522-1-lokeshgidra@google.com> References: <20240117223729.1444522-1-lokeshgidra@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 17 Jan 2024 14:37:29 -0800 Lokesh Gidra wrote: > In mfill_atomic_hugetlb(), mmap_changing isn't being checked > again if we drop mmap_lock and reacquire it. When the lock is not held, > mmap_changing could have been incremented. This is also inconsistent > with the behavior in mfill_atomic(). Thanks. Could you and reviewers please consider - what might be the userspace-visible runtime effects? - Should the fix be backported into earlier kernels? - A suitable Fixes: target?