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Fri, 01 May 2026 03:34:12 -0700 (PDT) Message-ID: <9efbd035-b40e-4155-8382-b42acff75a9e@kernel.dk> Date: Fri, 1 May 2026 04:34:11 -0600 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] ublk: reject FETCH from non-userspace context To: Ming Lei , linux-block@vger.kernel.org Cc: Caleb Sander Mateos , Uday Shankar References: <20260501085216.905401-1-tom.leiming@gmail.com> Content-Language: en-US From: Jens Axboe In-Reply-To: <20260501085216.905401-1-tom.leiming@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/1/26 2:52 AM, Ming Lei wrote: > __ublk_fetch() sets io->task to current, which is later checked > against io_uring_cmd_get_task() in ublk_uring_cmd_cancel_fn(). > With REQ_F_FORCE_ASYNC, the FETCH uring_cmd can be issued from > task work, which can be run from io_uring's fallback workqueue, > causing a task mismatch and triggering the WARN in cancel_fn. > > Reject FETCH if current is not a real userspace task, and it is > reasonable for failing it in case of io_uring fallback. I think this should be caught in ublk_ch_uring_cmd_cb(), which should not hit ublk_ch_uring_cmd_local() if tw.cancel is true. fallback work should just be terminated, not be issued. -- Jens Axboe