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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 338A8C433EF for ; Wed, 4 May 2022 13:03:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350168AbiEDNH2 (ORCPT ); Wed, 4 May 2022 09:07:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237497AbiEDNH0 (ORCPT ); Wed, 4 May 2022 09:07:26 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 877E2377E0 for ; Wed, 4 May 2022 06:03:50 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1651669429; 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=qnTydrMS1ksmehjR1Sl6xajLYwWe+zoyDgYNW/GZj1w=; b=RO2BH/TcggPsRNijCcOP8zR+Lo8UVQQ0WcBGQQ/AxGOcA/VecEAn7o+osJsn81GlCUVOB4 b8W0jiLwk8gz2TW1ST2HNCfZ9cnHW/o7t9BiKRVbUDTmP2VONzBwTuxCe8hS0EPtmnpljB /BEQkR/pUkO8tEoEktLRKgbHv+aY+qdPFGu64mJwbLqiFKFA5OJV5S5K0eCO1gTDNv/+rh 2JLbGmvjfHY39k9xE19cA2WrCcC4QodI2NoXAhSnRvyAI3yULTj86MmNJMH4dMs70zMyRc Kxuq9678kGZncg0zbeyhWcWHSh7Jf+IlEATiA0UNV+jW4YSEE/0/jere4EMztQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1651669429; 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=qnTydrMS1ksmehjR1Sl6xajLYwWe+zoyDgYNW/GZj1w=; b=Eyd/snTxo2U0d7A7rEeZjUIVMAZ6f+1uWn05fdJ1zNJyUxFJyfUIRXpa6uolhIJsaU0SBF lxshDIpJBoLXkADQ== To: Marcelo Tosatti Cc: linux-kernel@vger.kernel.org, Nitesh Lal , Nicolas Saenz Julienne , Frederic Weisbecker , Christoph Lameter , Juri Lelli , Peter Zijlstra , Alex Belits , Peter Xu , Daniel Bristot de Oliveira , Oscar Shiang Subject: Re: [patch v12 13/13] task isolation: only TIF_TASK_ISOL if task isolation is enabled In-Reply-To: References: <20220315153132.717153751@fedora.localdomain> <20220315153314.333646565@fedora.localdomain> <87zgk7x93h.ffs@tglx> Date: Wed, 04 May 2022 15:03:48 +0200 Message-ID: <87k0b1jvpn.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 03 2022 at 16:12, Marcelo Tosatti wrote: > On Wed, Apr 27, 2022 at 09:45:54AM +0200, Thomas Gleixner wrote: > It seems to be inline with the remaining TIF_ bits: > > if (ti_work & _TIF_NOTIFY_RESUME) > tracehook_notify_resume(regs); > > + if (ti_work & _TIF_TASK_ISOL) > + task_isol_exit_to_user_mode(); > + > > > And there is even: I know that the bit is defined, but that does still not make an argument. > By looking at the code, we see the sites where this bit is set are: Again. I'm able to read the patches myself. > Would you prefer an explanation, in words, when these bits are set, when > they are cleared? No. The point is that contrary to TIF_NOTIFY_RESUME and other TIF bits, this is going to end up being sprinkled all over the place. With the current vmstat quiesce that's limited, but it's bound to increase and spread simply because the whole thing has no semantics and it's all headed to be adhoc cure for the isolation itch of the day. Thanks, tglx