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 X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14594C433DF for ; Tue, 30 Jun 2020 18:30:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD01E20768 for ; Tue, 30 Jun 2020 18:30:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TBUNJpi1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390790AbgF3SaM (ORCPT ); Tue, 30 Jun 2020 14:30:12 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:41941 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732246AbgF3SaL (ORCPT ); Tue, 30 Jun 2020 14:30:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593541809; 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=7OCgH8gBQ1PrIfBItQcZbl5DDSqpXuCS2ZxQUU3Vu/M=; b=TBUNJpi1yshZvtnVEBuzYTn8Zl50rEtrZoY6A6/BTjQE/M25DLzT3NssHUX9OW5pnwpaxT DzLNsCmbArxP3B44GF21d/PfpKEaUqGy8rql26KvCJq1Rk5khonaFOEcr3PpJA9MQTuLIP F5A7FCNoWwZar6FyZ9lN/wlvXKjeeBk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-223-vUlTpLERMYC5hy90eKi4ZQ-1; Tue, 30 Jun 2020 14:30:07 -0400 X-MC-Unique: vUlTpLERMYC5hy90eKi4ZQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 10F468900B9; Tue, 30 Jun 2020 18:29:38 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.165]) by smtp.corp.redhat.com (Postfix) with SMTP id 7BF3860C81; Tue, 30 Jun 2020 18:29:35 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 30 Jun 2020 20:29:37 +0200 (CEST) Date: Tue, 30 Jun 2020 20:29:34 +0200 From: Oleg Nesterov To: Linus Torvalds Cc: Nicholas Piggin , Andi Kleen , Davidlohr Bueso , Jan Kara , Lukas Czerner , Linux Kernel Mailing List , Mel Gorman , Peter Zijlstra Subject: Re: wait_on_page_bit_common(TASK_KILLABLE, EXCLUSIVE) can miss wakeup? Message-ID: <20200630182933.GC26512@redhat.com> References: <1593396958.ydiznwsuu8.astroid@bobo.none> <20200629140245.GB20323@redhat.com> <1593482844.k3rh7s05o8.astroid@bobo.none> <20200630061708.GA21263@redhat.com> <1593505946.t0nxq8q8kj.astroid@bobo.none> <20200630105354.GB23871@redhat.com> <20200630113637.GC23871@redhat.com> <20200630115052.GD23871@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/30, Linus Torvalds wrote: > > On Tue, Jun 30, 2020 at 4:51 AM Oleg Nesterov wrote: > > > > On 06/30, Oleg Nesterov wrote: > > > > > > may be someting like this > > > > or this ... > > Guys, I'd suggest we either > > (a) do the minimal ugly one-liner workaround > > or > > (b) do something *much* more radical. I agree, and let me repeat I think your one-liner is fine. I just tried to discuss the possible alternatives to that on-liner for the start. > the wake_page_function() would actually do I swear, I too thought about changing wake_page_function() but got lost ;) The very fact it returns -1 if test_bit() is true suggests it can do more. Oleg.