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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 C692DC28CF6 for ; Fri, 3 Aug 2018 23:28:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 772C52178F for ; Fri, 3 Aug 2018 23:28:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 772C52178F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.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 S1732201AbeHDB0n (ORCPT ); Fri, 3 Aug 2018 21:26:43 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:47516 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732033AbeHDB0m (ORCPT ); Fri, 3 Aug 2018 21:26:42 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.9.92]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 30302CD0; Fri, 3 Aug 2018 23:28:19 +0000 (UTC) Date: Fri, 3 Aug 2018 16:28:18 -0700 From: Andrew Morton To: Minchan Kim Cc: LKML , Sergey Senozhatsky , Tino Lehnig , stable@vger.kernel.org, Jens Axboe Subject: Re: [PATCH 1/2] zram: remove BD_CAP_SYNCHRONOUS_IO with writeback feature Message-Id: <20180803162818.8c4719232d6dfece21ebea30@linux-foundation.org> In-Reply-To: <20180803025143.GA86818@rodete-desktop-imager.corp.google.com> References: <20180802051112.86174-1-minchan@kernel.org> <20180802141304.d0589ddc5f8213429ab3b565@linux-foundation.org> <20180803025143.GA86818@rodete-desktop-imager.corp.google.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 3 Aug 2018 11:51:43 +0900 Minchan Kim wrote: > > Is it legitimate to be altering the bdi capabilities at this level? Or > > is this hacky? > > Most of device's bdi capability seems to be static but there are few drivers > which can change capability. For example, BDI_CAP_STABLE_WRITES > > drivers/scsi/iscsi_tcp.c > drivers/md/raid5.c > > I believe it's driver itself advertisement stuff so I hope it's not hack. The bdi is per-disk (per-queue). So if zram changes the bdi for a particular partition then it is accidentally mucking with the other partitions as well, and it shouldn't do that. At least, I think that's how it works - it's been a while. Jens, wake up ;)