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Thu, 24 Sep 2026 07:19:23 -0700 (PDT) Message-ID: Date: Thu, 24 Sep 2026 08:19:22 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 12/17] exec: cancel io_uring requests before de_thread() To: Christian Brauner , Oleg Nesterov , Chris Mason , linux-fsdevel@vger.kernel.org Cc: Alexander Viro , Jan Kara , NeilBrown , Ingo Molnar , Peter Zijlstra , linux-mm@kvack.org, io-uring@vger.kernel.org, stable@vger.kernel.org References: <20260921-work-coredump-fixes-v3-0-8e4adb1619e6@kernel.org> <20260921-work-coredump-fixes-v3-12-8e4adb1619e6@kernel.org> Content-Language: en-US From: Jens Axboe In-Reply-To: <20260921-work-coredump-fixes-v3-12-8e4adb1619e6@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7D95C40004 X-Stat-Signature: 4sc9nj7373cyunmnk8yxiwj4qshxfnse X-HE-Tag: 1790259566-134717 X-HE-Meta: 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 xw4CP6jn Z7Env4InxeBTgKqupjEOGOaH+iBZuN371KEbe+ij6BZVAI+Yk98135qddrndlVm2Hx9UXMZuBhskD7Kc56Msqw38ohR+rsrvzCRrITmgKyxqz607XBznCPJlm2OpPjArjFMJxLHsm4aMUIEDjmwnAvUHsb6XOvGCyz7575L6gZmSX1zFCGdIamx2r3WyllN6LjJru8rGeStiNyE0o988XceOZhaQ6MMeFl37ya0fCRiY7GZwhi4HmQuU8x/tuZqiUz6+kSqHXtqk6rXjorKirtaTLQ8rDNwQhp17WBTgVQq4I226rZGS/X97l/HpB43igUT+LzaQk8/eTUsF+VR9Frkxc2drT4cyxMv5gEhpqUpzHpoD8QGI8Sx+Rrpm+jyTU+LduURVMS0UPXSF/eLTdnUi2Sz4zkTmDPaac5PdVIe+c1FhnQWdTtPkEgKGTgnVrfmXK1dqSJHe68jZ7t8UNmSE4WQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/21/26 7:45 AM, Christian Brauner wrote: > begin_new_exec() cancels the exec'ing thread's io_uring requests after > de_thread() made it the only thread in the thread-group. Now > io_uring_task_cancel() runs task work after. If it runs a > create_worker_cb() item then a io-wq queued on the thread before the > exec creates a new io-wq worker thread. > > Said thread joins the thread-group which de_thread() just took down. The > io-iwq sticks around until it notices that its workqueue is dying. But > code after de_thread() relies on being single-threaded. > > Move io_uring_task_cancel() before de_thread() but behind the point of > no return. Any worker created during task work run from > io_uring_task_cancel() is just a sibling thread that de_thread() will > take down and reap. > > Once io_uring_task_cancel() returned the thread has neither a task > context nor a workqueue left so nothing can add a thread behind > de_thread()'s back anymore. Reviewed-by: Jens Axboe -- Jens Axboe