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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483b820f718sm1428145e9.5.2026.02.23.10.14.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Feb 2026 10:14:45 -0800 (PST) Date: Mon, 23 Feb 2026 18:14:44 +0000 From: David Laight To: Oleg Nesterov Cc: Christian Brauner , Jann Horn , Linus Torvalds , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: pidfd && O_RDWR Message-ID: <20260223181444.1d87e3a2@pumpkin> In-Reply-To: References: <20260223-work-pidfs-autoreap-v4-0-e393c08c09d1@kernel.org> <20260223-work-pidfs-autoreap-v4-2-e393c08c09d1@kernel.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) 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 Mon, 23 Feb 2026 18:05:44 +0100 Oleg Nesterov wrote: > On 02/23, Oleg Nesterov wrote: > > > > Sorry for noise! > > Yes, but let me add more (off-topic) noise to this thread... > > pidfd_prepare() does pidfs_alloc_file(pid, flags | O_RDWR) and "| O_RDWR" > makes no sense because pidfs_alloc_file() itself does > > flags |= O_RDWR; > > I was going to send the trivial cleanup, but why a pidfs file needs > O_RDWR/FMODE_WRITE ? Or why any program that gets that far through the code 'wins' write access. David