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Wed, 03 Dec 2025 06:53:11 -0800 (PST) From: Jens Axboe To: Caleb Sander Mateos Cc: Uday Shankar , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20251202205745.3709469-1-csander@purestorage.com> References: <20251202205745.3709469-1-csander@purestorage.com> Subject: Re: [PATCH] io_uring/io-wq: always retry worker create on ERESTART* Message-Id: <176477359158.834078.5263900730628607784.b4-ty@kernel.dk> Date: Wed, 03 Dec 2025 07:53:11 -0700 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Mailer: b4 0.14.3 On Tue, 02 Dec 2025 13:57:44 -0700, Caleb Sander Mateos wrote: > If a task has a pending signal when create_io_thread() is called, > copy_process() will return -ERESTARTNOINTR. io_should_retry_thread() > will request a retry of create_io_thread() up to WORKER_INIT_LIMIT = 3 > times. If all retries fail, the io_uring request will fail with > ECANCELED. > Commit 3918315c5dc ("io-wq: backoff when retrying worker creation") > added a linear backoff to allow the thread to handle its signal before > the retry. However, a thread receiving frequent signals may get unlucky > and have a signal pending at every retry. Since the userspace task > doesn't control when it receives signals, there's no easy way for it to > prevent the create_io_thread() failure due to pending signals. The task > may also lack the information necessary to regenerate the canceled SQE. > So always retry the create_io_thread() on the ERESTART* errors, > analogous to what a fork() syscall would do. EAGAIN can occur due to > various persistent conditions such as exceeding RLIMIT_NPROC, so respect > the WORKER_INIT_LIMIT retry limit for EAGAIN errors. > > [...] Applied, thanks! [1/1] io_uring/io-wq: always retry worker create on ERESTART* commit: 777dfd696d3db9b7b08a41c3c03554ce0ba6c94e Best regards, -- Jens Axboe