From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3E6FFC7EE24 for ; Fri, 2 Jun 2023 19:23:30 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 3DBC08089E; Fri, 2 Jun 2023 19:23:29 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 3DBC08089E Authentication-Results: smtp1.osuosl.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=dDibgMqJ X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id U5NB6RpTedo5; Fri, 2 Jun 2023 19:23:28 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp1.osuosl.org (Postfix) with ESMTPS id DF10B84581; Fri, 2 Jun 2023 19:23:27 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org DF10B84581 Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id B2E5FC0037; Fri, 2 Jun 2023 19:23:27 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6C507C0029 for ; Fri, 2 Jun 2023 19:23:26 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 3A05084581 for ; Fri, 2 Jun 2023 19:23:26 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 3A05084581 X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jDzkrDjLyMk0 for ; Fri, 2 Jun 2023 19:23:25 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 8429B84582 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by smtp1.osuosl.org (Postfix) with ESMTPS id 8429B84582 for ; Fri, 2 Jun 2023 19:23:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685733804; 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=Hl/Yio++/nUxex1lxp6/0KZZRVMOQifT21+LBrMdJ5A=; b=dDibgMqJfHY9EacCDw9HaMdM6UMfkAAp8zCrNvBXj9IQB+EhzjdJ5IeQsYP5h29a+qqLYg 9UgRrvTZWwKyTeEgzxVVgNGRYFkRIfBNYB6Hf1n6IfvzyYzBwuHSE+uGjps+Gc9nVJw6US Cd7+Ncj1NIvl/hGEF4AtzLgAlSOcXHU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-136-s9DeVHr9PSiNgf7LjKdAhw-1; Fri, 02 Jun 2023 15:23:20 -0400 X-MC-Unique: s9DeVHr9PSiNgf7LjKdAhw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CD4BD85A5BA; Fri, 2 Jun 2023 19:23:19 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.50]) by smtp.corp.redhat.com (Postfix) with SMTP id B8E9CC154D7; Fri, 2 Jun 2023 19:23:16 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 2 Jun 2023 21:22:58 +0200 (CEST) Date: Fri, 2 Jun 2023 21:22:55 +0200 From: Oleg Nesterov To: Mike Christie Subject: Re: [PATCH 1/1] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression Message-ID: <20230602192254.GD555@redhat.com> References: <20230601183232.8384-1-michael.christie@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230601183232.8384-1-michael.christie@oracle.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Cc: axboe@kernel.dk, brauner@kernel.org, mst@redhat.com, linux-kernel@vger.kernel.org, linux@leemhuis.info, ebiederm@xmission.com, stefanha@redhat.com, nicolas.dichtel@6wind.com, virtualization@lists.linux-foundation.org, torvalds@linux-foundation.org X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" Hi Mike, sorry, but somehow I can't understand this patch... I'll try to read it with a fresh head on Weekend, but for example, On 06/01, Mike Christie wrote: > > static int vhost_task_fn(void *data) > { > struct vhost_task *vtsk = data; > - int ret; > + bool dead = false; > + > + for (;;) { > + bool did_work; > + > + /* mb paired w/ vhost_task_stop */ > + if (test_bit(VHOST_TASK_FLAGS_STOP, &vtsk->flags)) > + break; > + > + if (!dead && signal_pending(current)) { > + struct ksignal ksig; > + /* > + * Calling get_signal will block in SIGSTOP, > + * or clear fatal_signal_pending, but remember > + * what was set. > + * > + * This thread won't actually exit until all > + * of the file descriptors are closed, and > + * the release function is called. > + */ > + dead = get_signal(&ksig); > + if (dead) > + clear_thread_flag(TIF_SIGPENDING); this can't be right or I am totally confused. Another signal_wake_up() can come right after clear(SIGPENDING). Again, I'll try to re-read this patch, but let me ask anyway... Do we have a plan B? I mean... iirc you have mentioned that you can change these code paths to do something like if (killed) tell_the_drivers_that_all_callbacks_will_fail(); so that vhost_worker() can exit after get_signal() returns SIGKILL. Probably I misunderstood you, but it would be nice to avoid the changes in coredump/etc code just to add a temporary (iiuc!) fix. Oleg. _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization