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[141.239.149.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fbb6ab7c66sm21898105ad.121.2024.07.09.17.54.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jul 2024 17:54:16 -0700 (PDT) Sender: Tejun Heo Date: Tue, 9 Jul 2024 14:54:15 -1000 From: Tejun Heo To: Pavel Begunkov Cc: Oleg Nesterov , io-uring@vger.kernel.org, Jens Axboe , Andrew Morton , Christian Brauner , Tycho Andersen , Thomas Gleixner , linux-kernel@vger.kernel.org, Julian Orth , Peter Zijlstra Subject: Re: [PATCH 2/2] kernel: rerun task_work while freezing in get_signal() Message-ID: References: <1d935e9d87fd8672ef3e8a9a0db340d355ea08b4.1720368770.git.asml.silence@gmail.com> <20240708104221.GA18761@redhat.com> <62c11b59-c909-4c60-8370-77729544ec0a@gmail.com> <20240709103617.GB28495@redhat.com> <658da3fe-fa02-423b-aff0-52f54e1332ee@gmail.com> <20240709190743.GB3892@redhat.com> <20240709193828.GC3892@redhat.com> 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=us-ascii Content-Disposition: inline In-Reply-To: Hello, On Tue, Jul 09, 2024 at 08:55:43PM +0100, Pavel Begunkov wrote: ... > > > CRIU, I assume. I'll try it ... > > > > Than I think we can forget about task_works and this patch. CRIU dumps > > the tasks in TASK_TRACED state. > > And would be hard to test, io_uring (the main source of task_work) > is not supported > > (00.466022) Error (criu/proc_parse.c:477): Unknown shit 600 (anon_inode:[io_uring]) > ... > (00.467642) Unfreezing tasks into 1 > (00.467656) Unseizing 15488 into 1 > (00.468149) Error (criu/cr-dump.c:2111): Dumping FAILED. Yeah, the question is: If CRIU is to use cgroup freezer to freeze the tasks and then go around tracing each to make dump, would the freezer be enough in avoiding interim state changes? Using CRIU implementation is a bit arbitrary but I think checkpoint-restart is a useful bar to measure what should stay stable while a cgroup is frozen. Thanks. -- tejun