From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f52.google.com (mail-wr1-f52.google.com [209.85.221.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1C184182A74; Tue, 9 Jul 2024 19:55:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720554938; cv=none; b=U1yJRUWSU2ykYAbHk2sVq3lDMLaPzISkHCq/cb/eLjiHHoTSjmARHgy3WOFsISAcEsjITsXnPyt82KyyVa0UrZy+dCl44QqSznuUv4fNjm/2MvNwsJBEXkd3TC7gfW5P57/PtPuYrRbYjkbgS0daLDDxxFNV7yVYa+oB2b1BQ4Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720554938; c=relaxed/simple; bh=fX/KQ+mAl0LS1uvwZ5S2iSk6vGVLpLkxqGmAAdu8FJg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gPGEHdiAoTPjmzCkUKh9VfQnM+4/V0duG1uJ5GrsjLkwNCOJxsdNSbcQrDA0mhX6KB9fzq2OvE8n/UY9ck4AqTns3svDtVtMZ2UYR7xLCnUGV3H1ujrzEjA55YhMu939ctaIZcB4eV43lN0Tqyd1r7Sj75pDujIL8KjC/huW4RA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=UYi8hbCM; arc=none smtp.client-ip=209.85.221.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UYi8hbCM" Received: by mail-wr1-f52.google.com with SMTP id ffacd0b85a97d-36798779d75so4864006f8f.3; Tue, 09 Jul 2024 12:55:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1720554935; x=1721159735; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=tj8SXQ2T3v0Iau1Rc6pv6fU6a86nQKAkdshKGb1RYAY=; b=UYi8hbCMvA5lDAFSbgSv+0MRCPSuADFKiAw/0FR0bXVGG8LygoDrznTWlcAz9P7yzd njuk3OG9R8zvHKbgI5m29CB5ULLxYAew7llAJaSnyAqZ82FJCvmvbAfo7dvsHBL1v6/f PYx42onVwxrI/ZLhiNCwvE8tavbc05uHvKWXQO0f4Z+ueHUVhX64S2Tz49oIOJALdLqm Pi1geTD55SFcOric3s8O8TsIdnDHJdcGE8J1Zwk+6z/VzItgFhME/nWhh5ZTUtKwVXUT SQqndF1EgnPGxqe6FmPtF/XUe0p8p7xoMeM4lKNCiHRFuIRj+4JsNfCisz4VZ/U/ME9H 6b5g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720554935; x=1721159735; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=tj8SXQ2T3v0Iau1Rc6pv6fU6a86nQKAkdshKGb1RYAY=; b=s1fp6nPLuh8ip9d//4ezzdMbCNXu2akOttel9k6WMDmypP2s5f/bXMMOFAQ8io/x4N 3jFqqNcAbB4SYxq3kAVu/FembDq9pjGqrmpcBHJFAYhrOdGdbBcEJsoQXQjoeBKaqJsz leXH9mprg7lUAX5Aav8RmGostQyvT9FOgCObl4oVLEbiZXo6GF0SNLF76bkPylt9mXt/ 6EWAnBeY3X4MPxuO1GdioGj9bwjqOSjpKTuGKqm1SWiCR1z2LxAyQk9ho1hFwnsBdGOI 3z+bebbKUMCcEt4q9ICQHA2hd5bS5vZBcIH+N6MpB879Gq3THqMHt0ww9bzl9tzEI/9O Af9w== X-Forwarded-Encrypted: i=1; AJvYcCWwo3Q8ebEsdfW71R0rgU84DXJsgTRCUJrW4Ba4s0LPurNk8ywm4NrolSDCA22IVa1HX6T2WY/5J116G7dR2K85sJ1RzBKAefhqLWQfktcUOc9gARN2Ba2Fa/79Whf6RgHaEZfJbvA= X-Gm-Message-State: AOJu0YxmaOIe4ei/N6sbATqnGChyNZEv2ds0rjB+E0u6LVSqsQDjCZWE SJIFaKiXS3IEYaAyGmsqsfWlyZuzCknQuVDGafUnwpxOBiYu+/GZSGzx6A== X-Google-Smtp-Source: AGHT+IGuTvXzsHmHxXkl4S3WCqh+kTVelQjxbW/kK1xkaXuhWYCJfRW9rmD5vFzeiqnd56AGP6+eKQ== X-Received: by 2002:a05:6000:a8f:b0:366:f74f:abf0 with SMTP id ffacd0b85a97d-367cea67d3cmr3007527f8f.16.1720554935214; Tue, 09 Jul 2024 12:55:35 -0700 (PDT) Received: from [192.168.42.222] ([148.252.145.239]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-367cde7e192sm3429120f8f.9.2024.07.09.12.55.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Jul 2024 12:55:34 -0700 (PDT) Message-ID: Date: Tue, 9 Jul 2024 20:55:43 +0100 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] kernel: rerun task_work while freezing in get_signal() To: Oleg Nesterov Cc: Tejun Heo , io-uring@vger.kernel.org, Jens Axboe , Andrew Morton , Christian Brauner , Tycho Andersen , Thomas Gleixner , linux-kernel@vger.kernel.org, Julian Orth , Peter Zijlstra 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> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20240709193828.GC3892@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/9/24 20:38, Oleg Nesterov wrote: > On 07/09, Pavel Begunkov wrote: >> >> On 7/9/24 20:07, Oleg Nesterov wrote: >>> Hi Tejun, >>> >>> Thanks for looking at this, can you review this V2 patch from Pavel? > > Just in case, I obviously meant our next (V2) patch > > [PATCH v2 2/2] kernel: rerun task_work while freezing in get_signal() > https://lore.kernel.org/all/149ff5a762997c723880751e8a4019907a0b6457.1720534425.git.asml.silence@gmail.com/ > >>> Well, I don't really understand what can snapshot/restore actually mean... >> >> 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. >> ... but I'm inclined to think the patch makes sense regardless, >> we're replacing an infinite loop with wait-wake-execute-wait. > > Agreed. -- Pavel Begunkov