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 A5330F589C4 for ; Thu, 23 Apr 2026 12:52:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B5D556B0005; Thu, 23 Apr 2026 08:52:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B0DE26B008A; Thu, 23 Apr 2026 08:52:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9FCB86B008C; Thu, 23 Apr 2026 08:52:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 8A20A6B0005 for ; Thu, 23 Apr 2026 08:52:35 -0400 (EDT) Received: from smtpin23.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 508CE16011B for ; Thu, 23 Apr 2026 12:52:35 +0000 (UTC) X-FDA: 84689809470.23.32F0D48 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf11.hostedemail.com (Postfix) with ESMTP id 8054D40008 for ; Thu, 23 Apr 2026 12:52:33 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=FFKbgUMj; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1776948753; 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=SZJmbahbJYjm6PyqpxjneG+fiaKk2LDW0iLO0aYlf4o=; b=EjcmV79djVCKKoL8118KRUxxNWhVnxbpD77E9Ic7m6g6KFahPtYPJONPzMAGPDmtavMqR+ 2muVoCoLFTCl82FhW4ApzBakdkhZDAH7HbAinK+n3eP/q94A4CA1v8jmAO/vMm0iQXR+Cy Zl2264aOE3h5oqAy/v3wjh5J0QS91Vk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776948753; a=rsa-sha256; cv=none; b=qpuZg6L1B2QvmJTGC6PQwTpFZRXuZLRzPZjEuSUV/gV70k/xQbP9F8sAQpjIv1W1UtiHF0 vMiAVOGs6Sv2G/Z5DT/SrXqOwDLhczpzsTfuVhxML3hNrmo3dy9nH8k7UrdyqCd1WlydrB OoSEPuCTTpJlhhmtvzXzi1aMyNWA/HY= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=FFKbgUMj; spf=pass (imf11.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id D2EC26013B; Thu, 23 Apr 2026 12:52:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3F01C2BCAF; Thu, 23 Apr 2026 12:52:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776948752; bh=h0dIHU98MRwB37l3ilALHGus+i/AMpoovRfTb1CIX6M=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FFKbgUMjMYHXkRXq+vf1uwScuPWl8nWvt95X8tyi94yQanvWYXRUYBMFXWsU3lES+ 74RIRakc+e95FQ3vjrGnA/8Xh24I1cs3WdqUJXP0vUTvF4FJvlW2SdH/LMAkvQPHTj d+YQyNPF6fJmRy8XDSi1HDSGnwhOMcti85Ib1PPb8KlzRNaL/qtDulb6SirrNUFx/o +b1ihmhRpE0z9LJYLCG/8CNF9dqZL7WjZ8sQ3wkIhxLjUrZWd7z/GOK8Obl1WdxpLJ HXt00hk/IIXS44mZOVexB3w4WBfeF/Gr/0wiJk7uaf566NPpshW/8D+NGBjweSO4Jr HeUq0yG+rW2Ig== Message-ID: <62d88cde-efc0-48cb-be8d-813eda810343@kernel.org> Date: Thu, 23 Apr 2026 14:52:26 +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: Usama Arif , Alban Crequy Cc: 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> 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: <20260409142256.131676-1-usama.arif@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: mto4qosem1w6nkmxp7jy5t4nb3jyum9o X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 8054D40008 X-Rspam-User: X-HE-Tag: 1776948753-815672 X-HE-Meta: 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 wNG1Rekl 5Q6h3+TFGAk57b2DvSk3hFYpJ5jamICAZDvvkXOM887ij80ucljj2SkoOxxJi2T4bDTkonnT4O8LopOlJCP3NjIPgBx0DTS+h3R3WjjwUTZAE2KHBwm3HuKKTYBqEbxg7PVGSs9FUqzemDgs8xVJpLwLHqRY1Hx2SfsUajMiDNlLrdMeRJbzdPq7KVoutFjyaT5jBCeb3gH4XuRhuFwX4zhof4s3iKbqoX6UWgDnUYHLqjXeQpt8uo8ps9U9KiiQcKPBwhkz733qHlE/veb5lLnwijcwbvHUZfS+UtK9P0dizNMnf35OcEc5CfffcU0g16gXSYyeyMYcVm/lCSGqpV75Y5zqqC3LQSSWhPVYjXblkLCHyOWU6r9XOIg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >> >> /* Get process information */ >> - task = find_get_task_by_vpid(pid); >> + if (flags & PROCESS_VM_PIDFD) >> + task = pidfd_get_task(pid, &f_flags); >> + else >> + task = find_get_task_by_vpid(pid); >> + >> if (!task) { >> rc = -ESRCH; >> goto free_proc_pages; > > 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? -- Cheers, David