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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,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 846EAC28CF6 for ; Fri, 3 Aug 2018 05:23:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F6DB216ED for ; Fri, 3 Aug 2018 05:23:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="W8FUNbFk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2F6DB216ED Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com 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 S1727394AbeHCHRp (ORCPT ); Fri, 3 Aug 2018 03:17:45 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:38192 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726829AbeHCHRp (ORCPT ); Fri, 3 Aug 2018 03:17:45 -0400 Received: by mail-pg1-f194.google.com with SMTP id k3-v6so2287192pgq.5; Thu, 02 Aug 2018 22:23:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=k542X4pG5W7XIPYrOeJTmG6azuuDbAC/Kxa8+Np9U+g=; b=W8FUNbFkgMbNg9qzbrEFqEP/SekXtYymjLEaB4VcqNhohGXn+PWfdm3LZVB+wil7Dn 6Y1Md3oBGJabLXgLMRb5KqCCWPoW2gxrTzrWGksliVCnoQ0CFTMflRfHIdLcMcyiQD8K ZlNGJLY9irfIL3Hr/EdRjgHB5+An5PauCgAmyzOGfQ2rlxSI3kSOuVDwxnFDsg/vdEsh /vttA+2d1mP2RrTA3ASZQ+QBVXfix8AXCaW86F/w5MkI65EjbNcpjW6iba1kmoRhNGsx ZsnwMNv0vx2me4diM603eOnRgCgF/HBpbynnIgJiBHIk18V+71eIyrnBlha34eVU1qAp 5imw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=k542X4pG5W7XIPYrOeJTmG6azuuDbAC/Kxa8+Np9U+g=; b=q3ptnRjeD6fhhXvnDSaoq+61jRzrRNizWwLJnGGqS9TLWJQBSFXveaY77QCJ7vEb04 EDPzsT9UALd7LqV4aUTJT2mGKisGQFj+4M64SPBDk4jLiR4jOOFCe2iwyx0seQIVFJbs fZOAE6INGWOXZOnhPBtLMAISMwKGQPJ98tIZDj85Ei8g9RpljAQ9K6GrJ43lqqbwDM0b 7Rul+XcsnrfAmh4DyRLPQq/nGu1IMKIbfxPX1iTI+5TjNDboKy0R6hDOEkx22bpYKQzO Gc6JRSyTUK982HhlxtfmHH3CZM3Qxt0AM05YBI9e2tah6XECSMLN//aLa5xwG1pE3iMs lxoQ== X-Gm-Message-State: AOUpUlFC6uiS/nbMFC/+UqFwYCw2jr+FapqFYu9pvuP2pkyky1xcXtLM PpNUMz+yTWRb05G8hCYhIFQ0GoKU X-Google-Smtp-Source: AAOMgpdxFtR2vaoX7Dz3IyxNwn63HBAQyrgV7N+Z4dbkyXMf0+52aKLSovef403C8xBZgWPob35eew== X-Received: by 2002:a62:9d14:: with SMTP id i20-v6mr2727076pfd.3.1533273792068; Thu, 02 Aug 2018 22:23:12 -0700 (PDT) Received: from localhost ([175.223.10.158]) by smtp.gmail.com with ESMTPSA id q5-v6sm3368643pgv.61.2018.08.02.22.23.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 02 Aug 2018 22:23:10 -0700 (PDT) Date: Fri, 3 Aug 2018 14:23:06 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Andrew Morton , LKML , Tino Lehnig , stable@vger.kernel.org, Jens Axboe Subject: Re: [PATCH 1/2] zram: remove BD_CAP_SYNCHRONOUS_IO with writeback feature Message-ID: <20180803052306.GC502@jagdpanzerIV> References: <20180802051112.86174-1-minchan@kernel.org> <20180802141304.d0589ddc5f8213429ab3b565@linux-foundation.org> <20180803023929.GA7500@jagdpanzerIV> <20180803030019.GB86818@rodete-desktop-imager.corp.google.com> <20180803041302.GB502@jagdpanzerIV> <20180803045121.GC86818@rodete-desktop-imager.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180803045121.GC86818@rodete-desktop-imager.corp.google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (08/03/18 13:51), Minchan Kim wrote: > > AFAIK, onging writeback page couldn't freed so it was not writeabck problem. > > What I'm tryig to fix is read part. > If we use swapcache, it shouldn't be a problem either because swapcache > has a reference count and we should wait PG_lock release before the freeing > from the swapcache so there is no race condition. Hmm, any chance a WB device can be async on its own? We add a page to a new bio and submit it to another async device driver. Then we return back to the upper layer (swap), which can free a page before the device picks up a request. Can this happen? [..] > However, I decided, at this moment, going this simple way for > stable-material to solve #0 and #1 problems at the same time. Agreed. Thanks. -ss