From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 73F1B197A7E for ; Wed, 10 Jul 2024 19:12:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720638733; cv=none; b=sx5tPhL9IAV8qHeEdc6sElvm+gmbtgzWsyJLfahCB7uKNxFL3PrkOrJwUyNaQRLdIJjYhHwoOTx3CRGEJK8pIDCI0qZ4rSJzMXkgkfxQnoQ01Z/BQWeS7QkU3VLpjUUZy0X4ofh95FsUbCjFLwoLf/lfo2OHreeQbA2pBWFOT9I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720638733; c=relaxed/simple; bh=bDGvO62jYHv4lNM4mC2NUu6D837SU3bgt8PZd2SN7Rw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CTyTouxJBAdjiiBcFZHHj7TDJNm5FjaL+z0ATHKUpI9/UfgQ3FxMtYdmjZft6gE1DF9uxggamOQDsNrHc5Og7aX2UH2SjmA5v1hrrQ4xVLnzY7jYADDev/pmiqGMnEMJwoefVQ+kbm7BJpkK5fRNaP8d8N2bILRnFE9CIUIejQA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BAqyBvzA; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BAqyBvzA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1720638730; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=bDGvO62jYHv4lNM4mC2NUu6D837SU3bgt8PZd2SN7Rw=; b=BAqyBvzAzCvdYso+cYELbueVPGQbhVZmX0vl/OxNL/RatpBy+YYRxG2OxdQAWWa/Gx2m1Q Pi2INu5ol7/5g4kSp5SXY4zmqxotn2H//A/VrvJ3Cj02D8MzxyqtMlezccJZSvp6Z9a5AO jcYJzDunSyXjCvYy/0pEwz7vZP8APyM= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-96-BD8xhm5hPVKh_Kem2s7ygA-1; Wed, 10 Jul 2024 15:12:02 -0400 X-MC-Unique: BD8xhm5hPVKh_Kem2s7ygA-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 568511955BC4; Wed, 10 Jul 2024 19:11:58 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.169]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id BECBF19560AE; Wed, 10 Jul 2024 19:11:53 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 10 Jul 2024 21:10:21 +0200 (CEST) Date: Wed, 10 Jul 2024 21:10:16 +0200 From: Oleg Nesterov To: Pavel Begunkov 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 Subject: Re: [PATCH 2/2] kernel: rerun task_work while freezing in get_signal() Message-ID: <20240710191015.GC9228@redhat.com> References: <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> <933e7957-7a73-4c9a-87a7-c85b702a3a32@gmail.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: <933e7957-7a73-4c9a-87a7-c85b702a3a32@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On 07/10, Pavel Begunkov wrote: > > On 7/10/24 01:54, Tejun Heo wrote: > >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. > > Sounds like in the long run we might want to ignore task_work while > it's frozen, Just in case, this is what I have in mind right now, but I am still not sure and can't make a "clean" patch. If nothing else. CRIU needs to attach and make this task TASK_TRACED, right? And once the target task is traced, it won't react to task_work_add(TWA_SIGNAL). Oleg.