From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 CAD5014373F for ; Mon, 10 Jun 2024 16:19:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718036397; cv=none; b=hZqhvERKpfC01sEkQnfKpzFWhq3eSxmNuJao2N6YcZZ9/TJNbPMpKGaVQq1nV4vClTHrRnbct9HGZqvo8NZvvH7+fW8dIrFRsuUWmi3Z8aOnCSwMS3NehB68h6oI61BDltju58fbFdp/ODRED7vvoLzxlwh4IblvaxBLOuJSHS8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718036397; c=relaxed/simple; bh=UvPKv+li/SINxAK7aM9lX1lje5YFH7WAMPntdkSblq4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kvz9CtDrwm2vUYBrmdTSltKtacoPp9uXW7D87HTyDXsGRTRxfT0RwQvlJgOHdOCuB9Vy4X4pZdXy0heb/hPQaB2OmIcz1ShrfUk3g1A1RiJJnXlO9oLWpVvPRGihc6OU27+deTZlImADAR7EbGBFqjMWcKdHMcs7OK0fxmFf5io= 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=SWDVWxGl; arc=none smtp.client-ip=170.10.129.124 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="SWDVWxGl" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1718036394; 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=gf4fTgOHmlHgU0q+hImhFWNpPhswAm3czG7DXf3LyZU=; b=SWDVWxGlxLTcAYJFkjICJO5abWNh9X3CUKDprOiZCh35P5BdvmKQna56kK8+I/zoC03keR hIaw+RccqBGM2n9ZgYBnMatwBFY0K1lqBeP5HFzEIoqqS3Ee8EBWXzQdUBcaxlUDaR2+Ul 7x1Fz+LX/wajj/4Q4mcvk//0B0/3yBs= Received: from mx-prod-mc-05.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-587-3Luzm_U-PoqUbBNU8riUcg-1; Mon, 10 Jun 2024 12:19:51 -0400 X-MC-Unique: 3Luzm_U-PoqUbBNU8riUcg-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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6D9B319560AD; Mon, 10 Jun 2024 16:19:50 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.117]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 59E5D19560AB; Mon, 10 Jun 2024 16:19:47 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 10 Jun 2024 18:18:20 +0200 (CEST) Date: Mon, 10 Jun 2024 18:18:17 +0200 From: Oleg Nesterov To: "Eric W. Biederman" Cc: Andrew Morton , Tejun Heo , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/1] exit: kill signal_struct->quick_threads Message-ID: <20240610161816.GE20640@redhat.com> References: <20240609142342.GA11165@redhat.com> <87r0d5t2nt.fsf@email.froward.int.ebiederm.org> <20240610152902.GC20640@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20240610152902.GC20640@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On 06/10, Oleg Nesterov wrote: > > > At the moment I am staring at wait_task_zombie and trying to understand > > how: > > > > status = (p->signal->flags & SIGNAL_GROUP_EXIT) > > ? p->signal->group_exit_code : p->exit_code; > > > > works without any locks or barriers. > > Agreed, at first glance this looks worrying without siglock... I'll try > to take a look, perhaps we can simply kill the SIGNAL_GROUP_EXIT check, > not sure. Still not sure, will check tomorrow, but probably yes. We can rely on the the exit_state == EXIT_ZOMBIE check in the caller and tasklist_lock. OTOH, we should probably take ptrace into account... In short, I am still not sure ;) but I agree this code needs some changes, the comments at least. > But this patch should not make any difference ? Yes. Oleg.