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=-2.4 required=3.0 tests=DKIM_SIGNED, MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID,USER_AGENT_MUTT autolearn=ham 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 37FCDC28CF6 for ; Wed, 25 Jul 2018 03:02:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF8CA20844 for ; Wed, 25 Jul 2018 03:02:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fa6+4QJs" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF8CA20844 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726122AbeGYEMQ (ORCPT ); Wed, 25 Jul 2018 00:12:16 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:44105 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725820AbeGYEMQ (ORCPT ); Wed, 25 Jul 2018 00:12:16 -0400 Received: by mail-pg1-f194.google.com with SMTP id r1-v6so4245539pgp.11 for ; Tue, 24 Jul 2018 20:02:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=sOqjT5qmJX81JGsm2ome1Z9Xe+pvDRGlNEfx+NRFyrM=; b=fa6+4QJs6Er5MpXMxdwWNOhsKfqQGgVdxJ56Hs5Fv+XZ+CWn1HvkGVYPeGmJNlbpoG hWgGP5rcAECMNfQVBppXHtEx11Q91CNWWs9J5FUOY7xVGC9rW0sKdF3XnfWznG+hxXhP yNEH5dp5j/cntloAVy480xC4nlvn9wJRnaAdlWgYguu0HQIdAC/aKEnFT9fl/5HLyeDp jIlvbYd9p6c6X0Dn1YbCkvjUB6zaoo6gv8QmXczwMw8glCj+7PWqwpXpZ83xev5nUvlq VPp9cbM0KnIUtLtsnwga/vXHMrvT1tNFdCw8tQDt3cx6P0fTVXWIfPH03lus6mqCA0Bu CC7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=sOqjT5qmJX81JGsm2ome1Z9Xe+pvDRGlNEfx+NRFyrM=; b=XQ2WwDC2NZyQigwAidh7JUzrJ4PCr8FxnWLjmWo2SFg8PKnoYZLlJClN7HF4RADZLS Ar2/qz8o5iKtF26lL2/YpRFsxE2fTfEiaHX6Ic0K8xpnSosqU4m0b6d6y5JMryFZgtKT cEOUBc5hieXrq2HCRBXBh3fx8mPSmfECgDbnX7dp7NMpEP5Ttv4SBwEpEECvb8PdG9oS j+TnxMzcl7vIss4o4RcHXk96SbOCXwMUi3j/IoLV8EfAZuR7yF2JdAQQxgrqftLMs4oV urNjfbCp+OjDQOj/xqvN8Sf5bt4LL3PRjKWL8EodhctLMqbUg4VjQbmjB+0SF74Qnu3G PI3Q== X-Gm-Message-State: AOUpUlE8rbyRRFcPW7sY/xjYgJgZ2B2XCwBQ/Viewx/3/WPcuxaDf2wr PuqD1sLvCLz38QsbeK8agjg= X-Google-Smtp-Source: AAOMgpdmvtFwZ2+ttB2fHFOP9SN5EX+XGhkcfmUHjef/3kgNEwDbX4RLzHm0FSqHnkze6kM/OzwIXQ== X-Received: by 2002:a62:642:: with SMTP id 63-v6mr20404586pfg.222.1532487763460; Tue, 24 Jul 2018 20:02:43 -0700 (PDT) Received: from rodete-desktop-imager.corp.google.com ([2401:fa00:d:10:affa:813f:5380:6613]) by smtp.gmail.com with ESMTPSA id j191-v6sm22820882pfc.136.2018.07.24.20.02.40 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 24 Jul 2018 20:02:41 -0700 (PDT) Date: Wed, 25 Jul 2018 12:02:37 +0900 From: Minchan Kim To: Matthew Wilcox Cc: Tino Lehnig , ngupta@vflare.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Andrew Morton Subject: Re: Zram writeback feature unstable with heavy swap utilization - BUG: Bad page state in process... Message-ID: <20180725030237.GA105976@rodete-desktop-imager.corp.google.com> References: <0516ae2d-b0fd-92c5-aa92-112ba7bd32fc@contabo.de> <20180724010342.GA195675@rodete-desktop-imager.corp.google.com> <20180725013250.GA66792@rodete-desktop-imager.corp.google.com> <20180725015502.GA16271@bombadil.infradead.org> <20180725021657.GA87819@rodete-desktop-imager.corp.google.com> <20180725023532.GB16271@bombadil.infradead.org> <20180725025106.GA99093@rodete-desktop-imager.corp.google.com> <20180725025525.GD16271@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180725025525.GD16271@bombadil.infradead.org> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 24, 2018 at 07:55:25PM -0700, Matthew Wilcox wrote: > On Wed, Jul 25, 2018 at 11:51:06AM +0900, Minchan Kim wrote: > > On Tue, Jul 24, 2018 at 07:35:32PM -0700, Matthew Wilcox wrote: > > > There is NOTHING in a union with _refcount. > > > > Confusing. Matthew, what am I missing? > > > > Before: > > > > counters consumes 8 bytes > > units and _refcount consumes each 4 bytes so memory space is not overlapped. > > Correct. _mapcount is at offset 24, as is units. _refcount is at offset 28. > > > union { > > unsigned long counters; > > struct { > > union { > > atomic_t _mapcount; > > int units; /* SLOB */ > > }; > > atomic_t _refcount; > > }; > > }; > > > > > > After: > > > > Now, units is overlapped with _refcount and _mapcount. > > No. units is at offset 24, as is _mapcount. But _refcount is still at > offset 28. Ah, got it what you mean. Sorry for the noise, Matthew. > > > union { > > unsigned long counters; > > int units; /* SLOB */ > > struct { /* Page cache */ > > atomic_t _mapcount; > > atomic_t _refcount; > > }; > > };