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 smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 6585EC77B75 for ; Mon, 22 May 2023 12:31:00 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id C275360E82; Mon, 22 May 2023 12:30:59 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org C275360E82 Authentication-Results: smtp3.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=DvCtZIU4 X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id pfbPKiGNu6rB; Mon, 22 May 2023 12:30:59 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp3.osuosl.org (Postfix) with ESMTPS id 6C99961136; Mon, 22 May 2023 12:30:58 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 6C99961136 Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3BCF5C0036; Mon, 22 May 2023 12:30:58 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id DF93AC002A for ; Mon, 22 May 2023 12:30:56 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id B39EF61136 for ; Mon, 22 May 2023 12:30:56 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org B39EF61136 X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id XrfiqGatk0Tj for ; Mon, 22 May 2023 12:30:55 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 9B0FE60E82 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by smtp3.osuosl.org (Postfix) with ESMTPS id 9B0FE60E82 for ; Mon, 22 May 2023 12:30:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684758653; 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=XLKVwpsofT3fO0KfbhEhMNwUy6j+Hh9Xz3u/5JzJISE=; b=DvCtZIU4wtlWL4DGHYmeTSFze0CrdwreZTgfezDsIVW44ab6QO2EsRGPB+iL5eTnlFOiJy uqhri2l2nW0HQEmocbw6CsAZy76GEv+RxFsYnxFnJNifAbLEqxi2AW/AtWLR0Y0cFF4PRg 5MI7TJaOMTbSdFvyVVQl76sGeYMIx+4= 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-612-y0yXY8u3NEe6cP21B_llfw-1; Mon, 22 May 2023 08:30:50 -0400 X-MC-Unique: y0yXY8u3NEe6cP21B_llfw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D051B185A78F; Mon, 22 May 2023 12:30:49 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.202]) by smtp.corp.redhat.com (Postfix) with SMTP id BD2D7407DEC3; Mon, 22 May 2023 12:30:46 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 22 May 2023 14:30:33 +0200 (CEST) Date: Mon, 22 May 2023 14:30:29 +0200 From: Oleg Nesterov To: Mike Christie Subject: Re: [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression Message-ID: <20230522123029.GA22159@redhat.com> References: <20230522025124.5863-1-michael.christie@oracle.com> <20230522025124.5863-4-michael.christie@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230522025124.5863-4-michael.christie@oracle.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 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" Confused, please help... On 05/21, Mike Christie wrote: > > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -338,6 +338,7 @@ static int vhost_worker(void *data) > struct vhost_worker *worker = data; > struct vhost_work *work, *work_next; > struct llist_node *node; > + bool dead = false; > > for (;;) { > /* mb paired w/ kthread_stop */ > @@ -349,8 +350,22 @@ static int vhost_worker(void *data) > } > > node = llist_del_all(&worker->work_list); > - if (!node) > + if (!node) { > schedule(); > + /* > + * When we get a SIGKILL our release function will > + * be called. That will stop new IOs from being queued > + * and check for outstanding cmd responses. It will then > + * call vhost_task_stop to tell us to return and exit. > + */ But who will call the release function / vhost_task_stop() and when this will happen after this thread gets SIGKILL ? > + if (!dead && signal_pending(current)) { > + struct ksignal ksig; > + > + dead = get_signal(&ksig); > + if (dead) > + clear_thread_flag(TIF_SIGPENDING); If you do clear_thread_flag(TIF_SIGPENDING), then why do we need 1/3 ? Also. Suppose that vhost_worker() dequeues SIGKILL and clears TIF_SIGPENDING. SIGSTOP, PTRACE_INTERRUPT, freezer can come and set TIF_SIGPENDING again. In this case the main for (;;) loop will spin without sleeping until vhost_task_should_stop() becomes true? Oleg. _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization