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 15BD7F589DC for ; Thu, 23 Apr 2026 14:17:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6AC8B6B0092; Thu, 23 Apr 2026 10:17:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 682CF6B0093; Thu, 23 Apr 2026 10:17:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 598CB6B0095; Thu, 23 Apr 2026 10:17:25 -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 49D926B0092 for ; Thu, 23 Apr 2026 10:17:25 -0400 (EDT) Received: from smtpin23.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay04.hostedemail.com (Postfix) with ESMTP id EC5EC1A01B0 for ; Thu, 23 Apr 2026 14:17:24 +0000 (UTC) X-FDA: 84690023208.23.367BA49 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf04.hostedemail.com (Postfix) with ESMTP id EDF5B40017 for ; Thu, 23 Apr 2026 14:17:22 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="XeKL7y/G"; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776953843; 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-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=y2UA4f7wSXZ4/Bo80ObO/SE71m2E320Jl4CNWIv04cU=; b=7YyRFjeuv7g6Du9yPikVs6iEceMl4NO2ELwQ2PohpAVBM4+vslmtCv1bxHP8B+8kvxSpQt l7Yh/dKVAr7WasMk8oB4mwINQGG8Ds2LW4zmTaHOq/MN7RgpddVfJ6g97b/QrAU7Lk6L2J H90nLgrJm8EAqIFAFjR9IOSEqxq3Rr8= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="XeKL7y/G"; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776953843; a=rsa-sha256; cv=none; b=5pcmkL16lMLRwgXWfUIAo2CC4yyTyR0h6tLpswgmCLcgHx0N/vgbRDHfPoqkdzkB9QhwYQ Ohe04MauOswMx14wu+ingCaZTSnRNdSPFIfmXfdb1/XORF1pPTbq7bOMrUR2k6iCKPdd4p hA/NUNovbFgRxIBWnI3HKwwxkU1bLaQ= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id DBD6E442E7; Thu, 23 Apr 2026 14:17:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2A80C2BCAF; Thu, 23 Apr 2026 14:17:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776953841; bh=HYlxK/A4zhqyWVJs4vRBWAO2MAfjEq9L8+wa2Bhw8rY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=XeKL7y/GC7ftp33dfqEyR3pNNDrerNvqacH7Vee2ePfHEFzvCo9UeD3+oX+yIfPAO ILHF0doDwuqwdFiDcGq5ONDas/j7G5rCNU3mJBh+Wj1Gin+JpNVzp1RiwfTxN8DMHc /HF339qJxVPKpn9oeZzMTax2CpJp/me8QPrN4JRPSEPX10dUyi8NEy/oT0oo3L2Kgj FCoPKkE02uZNnSACiTs7gs6oIeS1wdC+Ta/Atdl9oZFu6XQxUcHuoqYQMhtcvKhZ+i ty92ArzBL6XrjbhEy4axVu7tCV/mDyNNZioj3i8Vy91PP7cxU05xZtV830I7H13FBF QHDKiozo6ZBbA== Message-ID: <07f546eb-e523-4742-a8b1-ab830ec4d0d0@kernel.org> Date: Thu, 23 Apr 2026 16:17:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm/process_vm_access: pidfd and nowait support for process_vm_readv/writev To: David Laight Cc: Usama Arif , Alban Crequy , Andrew Morton , Christian Brauner , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Alban Crequy , Peter Xu , Willy Tarreau , linux-kselftest@vger.kernel.org, shuah@kernel.org References: <20260409142256.131676-1-usama.arif@linux.dev> <62d88cde-efc0-48cb-be8d-813eda810343@kernel.org> <20260423150423.1a428820@pumpkin> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260423150423.1a428820@pumpkin> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: EDF5B40017 X-Stat-Signature: s3it3bz7r7h8zz9u4szanw4ia9ehm9jd X-Rspam-User: X-HE-Tag: 1776953842-228688 X-HE-Meta: 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 wy1j251e eF9ZtVnY29K1Q6rlOF/Ossjg8w39pEotyordj85zzE81jf1MNAGTp/F+/7bFYqbvMHnM8jti+fA9iRk/BDayJnAf/yHHATfeYnhvzOv7dQ/7LMYfJrJ3RlPkjnlUzDOf0wmFjl4phAp3ELhDNGZw8gMyvnKB++c6Jlck0m8E6238ktoFp+B/ZJH+DqV8C9WlZyha1maklkF0lM2Hx3yikVmBengLI8fpj5oUm38N0O3K+r0EnJBSz9Cfd4dj9SW256eyozBV2gQljwSquhAjNhctJEzC31YActkPO6rDpSrE2W57MF6QF1dDAs6MEGvvcvohOdVKZVCH4C15CUY9q3ReqiRuWLGY5BgfVdMreY8vuQQkDrwiLomMfKG9/DsLI113tYVv1tfYqRfqZKm++5VwC2eHwts7Y72O8EFdkWKqFWx0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/23/26 16:04, David Laight wrote: > On Thu, 23 Apr 2026 14:52:26 +0200 > "David Hildenbrand (Arm)" wrote: > >>> >>> pidfd_get_task() returns ERR_PTR() on failure (e.g. ERR_PTR(-EBADF)), >>> but the code checks "if (!task)" which only catches NULL. An invalid >>> pidfd will cause mm_access() and put_task_struct() to dereference an >>> error pointer, crashing the kernel. >> >> Yes. Should we add proper selftests that exercise these code paths? >> Just to clarify: I meant adding more tests to patch #2 that trigger the issue here. > > Probably worth checking what happens when a 64bit process tries to > read high addresses of a 32bit process. > I guess these are a bit harder to write, but would certainly be useful. -- Cheers, David