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 9AC30C433E0 for ; Mon, 29 Jun 2020 19:14:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DE86206E9 for ; Mon, 29 Jun 2020 19:14:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="b+L75C/2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730930AbgF2TOj (ORCPT ); Mon, 29 Jun 2020 15:14:39 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:51586 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731819AbgF2TOf (ORCPT ); Mon, 29 Jun 2020 15:14:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593458074; 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=uaWG/Hwtc/IuZbOB2qwDYiIrGK8VtDdNu+bH/o2E7C4=; b=b+L75C/29nuPnY7P7vp/5K56gpxYUxfEN2LmOxKSBtEOuNgEMLivk6ByH5mFPrwYyNDxR3 NMID2N3Uvn/mpzlvc9y65GCIjI8JAcUXXl4sWls5AD785df12+oqamND3tSY/Tcvq4qtEY RGChheQHJVzCDsN3PmvjYVt3PHomg1A= 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-35-4UE05tubOXSAa1_zfb3LrQ-1; Mon, 29 Jun 2020 11:13:46 -0400 X-MC-Unique: 4UE05tubOXSAa1_zfb3LrQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 22F07107ACCA; Mon, 29 Jun 2020 15:13:45 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.58]) by smtp.corp.redhat.com (Postfix) with SMTP id BFEE2101E5A2; Mon, 29 Jun 2020 15:13:42 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 29 Jun 2020 17:13:44 +0200 (CEST) Date: Mon, 29 Jun 2020 17:13:41 +0200 From: Oleg Nesterov To: Linus Torvalds Cc: Peter Zijlstra , Nick Piggin , Mel Gorman , Jan Kara , Davidlohr Bueso , Andi Kleen , Lukas Czerner , Linux Kernel Mailing List Subject: Re: wait_on_page_bit_common(TASK_KILLABLE, EXCLUSIVE) can miss wakeup? Message-ID: <20200629151340.GC20323@redhat.com> References: <20200624161142.GA12184@redhat.com> <20200624162042.GA12238@redhat.com> <20200626154313.GI4817@hirez.programming.kicks-ass.net> 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 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/27, Linus Torvalds wrote: > > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1150,6 +1150,12 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q, > io_schedule(); > > if (behavior == EXCLUSIVE) { > + /* > + * Make sure we don't get any exclusive wakeups > + * after this point! > + */ > + __set_current_state(TASK_RUNNING); > + smp_mb__before_atomic(); > if (!test_and_set_bit_lock(bit_nr, &page->flags)) > break; > } else if (behavior == SHARED) { FWIW, Reviewed-by: Oleg Nesterov