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Howlett" , Vlastimil Babka , 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, Usama Arif , David Laight Subject: Re: [PATCH v3 1/2] mm/process_vm_access: pidfd and nowait support for process_vm_readv/writev Message-ID: References: <20260428122826.339550-1-alban.crequy@gmail.com> <20260428122826.339550-2-alban.crequy@gmail.com> <8b29da5b-e260-4b77-a640-8abb447291d1@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8b29da5b-e260-4b77-a640-8abb447291d1@kernel.org> X-Rspam-User: X-Rspamd-Queue-Id: A42F118000D X-Rspamd-Server: rspam04 X-Stat-Signature: ydcbo89mcth9kxpi45suaxbi4gry9sf5 X-HE-Tag: 1777444924-858588 X-HE-Meta: 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 xQ+40X9I 6iaL08CMsUJcWoqC5iGFnmJMZMVZUjgXqcCzqaDCIwj46XUOD9J1aHrd60nnphUsUe8YQGyGTAoXK1D4sabcqDY1WUVl+9tr4PlnEVjtRIeNHFw7ENQVRfasnRMR4YUJv56rKgnQarOgXQhhpb6dxBRlqicM+V3bRnYlwhw1FpRzbS9+OWG54M/pEXd+VK+n5OiUEhk8c6nBlMlnAYQLnu4l0qoEjO1Ryo4Jf4gAUcZ4dapGfaasPNnfNZIxK8rhQME5sx31xkeoblQ9OuQTcYZe8odnpzMNsqQhhUs3qIFyIBPMTanObVXAbBMUtIROMo+efEckGllu6HgCIsNunNcz9USRYGpqczJodCKTiVOXCwu7xJkqzK/dfk5bNjVwfKNHOsWCD7XVk6eY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Apr 28, 2026 at 10:05:49PM +0200, David Hildenbrand (Arm) wrote: > On 4/28/26 14:28, Alban Crequy wrote: > > From: Alban Crequy > > @@ -194,10 +202,18 @@ static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter, > > } > > > > /* Get process information */ > > - task = find_get_task_by_vpid(pid); > > - if (!task) { > > - rc = -ESRCH; > > - goto free_proc_pages; > > + if (flags & PROCESS_VM_PIDFD) { > > + task = pidfd_get_task(pid, &f_flags); > > + if (IS_ERR(task)) { > > + rc = PTR_ERR(task); > > This could return -EBADF or -ESRCH. We should document both in the man page. (or > decide to always return -ESRCH, dunno) I'm for documenting both in the man page to let userpsace see what went wrong. > -- > Cheers, > David -- Sincerely yours, Mike.