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,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 7EB91C3A589 for ; Thu, 15 Aug 2019 17:35:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51DCA2064A for ; Thu, 15 Aug 2019 17:35:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565890503; bh=jZQNTS7JeYOtb34meyZbI96CYuPKeV0gPhc+9hftCpA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Ol2yHiDesDQ8Sjrf2e2Amexog/ba4G8/P9x1aJnX73iq+d65Alo1xWLVBhobmuijI xP+b37598w09RrEj2XuzkuurpFKnp/ni2tZh9ee4F/SjuUrvIkk88n9mNd76yeE8Jr ReMiOPUE4c143BIgqe5S3w4LQ8hns8Yy/PXmXYPY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732065AbfHORfC (ORCPT ); Thu, 15 Aug 2019 13:35:02 -0400 Received: from mail-qt1-f174.google.com ([209.85.160.174]:42981 "EHLO mail-qt1-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726203AbfHORfC (ORCPT ); Thu, 15 Aug 2019 13:35:02 -0400 Received: by mail-qt1-f174.google.com with SMTP id t12so3148048qtp.9; Thu, 15 Aug 2019 10:35:02 -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=2ZSbStm7AbDlXUhKJSg3L8e0NLU9fEch1EIrUdDIspw=; b=gfG9UzxThCigCBaKBs4lpzT/DQERj6tRex3zsyhWWtC5mNoRtHY0KVhl1Eusttge/6 gTa0XkfdlzW5xd0gUiYLS0otjvybVrqu20zk5hDPLSTPCA42Rld4afQ1YnK0eHOHfAvx XchEDv5NXEmt5CcVefyG3DYRIVtmobbNBMwDKn8GtVpQKOTUK9LexdYi+sTLctzGyNxe TYWo1VhCO+dbNXL98G4TvRHHRh6LRAXKcuaLZV2w+2AsiVgzdSbIulXiEvLbHnLjM9/r FAzV2hVYQhnbnkcDrUmUq0qh4De17xFpCKGwoLpS0fpwYewK6JYlJy0m2NMukOuaQRKo U9Ag== 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=2ZSbStm7AbDlXUhKJSg3L8e0NLU9fEch1EIrUdDIspw=; b=c6DeMdCfgr+r15p7LEkHKlY1hQ37rACT/jyfedDPlBf1NrkBrzgJk66QROvwD5yo9N 71VpVo+EHD9GrSl18nYWCZS3cSOyz+tBElFXf2VTuOk+dz/iIRK72OdZP1pdPuGmep67 Wc1jn/epWHFPvkXcew9SdsctzaksMFGQWEKmLrV/380m550PvruIg0meC9+hbD647PE1 2kbD4mClYNIx66pcUN4SQANCC3HYOC+P1rvngtefb7OIDI/G12C1vv/qrupKnUlIhBdn zMlLQWz7UOhVjZYJgycUqNxteR2IUP3GLkIN28mnCB60weUn/gasfdPFeyMSMyuL+br1 4k9A== X-Gm-Message-State: APjAAAWWCMR1VIw2YUwsflUOnAnwQLNXF/vMpi8efW+FvQ758NpASctW Jl3wdBI94LQ9GvcVsuYCtyc= X-Google-Smtp-Source: APXvYqzlu7N6cRvS0ocSXBCf6KXcLrqKgjEDpi8R5FqcX+e5okBZTdTHSPWh9rbIZLoOA+UBtTrZqw== X-Received: by 2002:a0c:e588:: with SMTP id t8mr4042293qvm.179.1565890501439; Thu, 15 Aug 2019 10:35:01 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::1:25cd]) by smtp.gmail.com with ESMTPSA id y194sm1687796qkb.111.2019.08.15.10.35.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Aug 2019 10:35:00 -0700 (PDT) Date: Thu, 15 Aug 2019 10:34:59 -0700 From: Tejun Heo To: Jan Kara Cc: axboe@kernel.dk, hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, guro@fb.com, akpm@linux-foundation.org Subject: Re: [PATCH 2/4] bdi: Add bdi->id Message-ID: <20190815173459.GE588936@devbig004.ftw2.facebook.com> References: <20190803140155.181190-1-tj@kernel.org> <20190803140155.181190-3-tj@kernel.org> <20190815144623.GM14313@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190815144623.GM14313@quack2.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hello, On Thu, Aug 15, 2019 at 04:46:23PM +0200, Jan Kara wrote: > Although I would note that here you take effort not to recycle bdi->id so > that you don't flush wrong devices while in patch 4 you take pretty lax > approach to feeding garbage into the writeback system. So these two don't > quite match to me... So, I was trying to avoid systemic errors where the wrong thing can be triggered repeatedly. A wrong flush once in a blue moon shouldn't be a big problem but if they can be triggered consistently by some pathological behavior, it's an a lot bigger problem. Thanks. -- tejun