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 9E49FC433DF for ; Tue, 30 Jun 2020 10:54:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 747672073E for ; Tue, 30 Jun 2020 10:54:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="jHFSgG54" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732654AbgF3KyJ (ORCPT ); Tue, 30 Jun 2020 06:54:09 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:28648 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729377AbgF3KyI (ORCPT ); Tue, 30 Jun 2020 06:54:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593514447; 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=G4bVBTJM9ZL7UUtLFxlQYgchfUUyg3SPUtd0RzryWjg=; b=jHFSgG54JlJhX216P53DPjawLlK47a+KoDUw7XLUp/PyUrX9XADCY0d+1Zpq+5o9WyyBSZ WBawNhClMt0K1ExsWqSwjJwmdSR+I3dUQQjJKvVU5Pe3D6njTIBzCpbg3wvoa+vrPrauao aeFv5qqdxUJJMtbAAW96+ZKuNl274rI= 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-63-gCD4jmLUMBmpjZctxH1XUA-1; Tue, 30 Jun 2020 06:54:03 -0400 X-MC-Unique: gCD4jmLUMBmpjZctxH1XUA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6FAC2107ACCA; Tue, 30 Jun 2020 10:54:01 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.195.229]) by smtp.corp.redhat.com (Postfix) with SMTP id B0E6D2B472; Tue, 30 Jun 2020 10:53:56 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 30 Jun 2020 12:54:01 +0200 (CEST) Date: Tue, 30 Jun 2020 12:53:55 +0200 From: Oleg Nesterov To: Nicholas Piggin Cc: Andi Kleen , Davidlohr Bueso , Jan Kara , Lukas Czerner , Linux Kernel Mailing List , Mel Gorman , Peter Zijlstra , Linus Torvalds Subject: Re: wait_on_page_bit_common(TASK_KILLABLE, EXCLUSIVE) can miss wakeup? Message-ID: <20200630105354.GB23871@redhat.com> References: <20200624161142.GA12184@redhat.com> <20200624162042.GA12238@redhat.com> <20200626154313.GI4817@hirez.programming.kicks-ass.net> <1593396958.ydiznwsuu8.astroid@bobo.none> <20200629140245.GB20323@redhat.com> <1593482844.k3rh7s05o8.astroid@bobo.none> <20200630061708.GA21263@redhat.com> <1593505946.t0nxq8q8kj.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1593505946.t0nxq8q8kj.astroid@bobo.none> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/30, Nicholas Piggin wrote: > > My patch is what actually introduced this ugly > bit test, but do we even need it at all? If we do then it's > under-commented, I can't see it wouldn't be racy though. Can we just > get rid of it entirely? But then we will need to move io_schedule() down, after test_and_set_bit(). And we will have the same problem with task->state != RUNNING. Plus more complications with "behavior == DROP". Oleg.