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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 70348C0044D for ; Thu, 12 Mar 2020 03:00:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8531520754 for ; Thu, 12 Mar 2020 03:00:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="QUV+09ZD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8531520754 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BDAE36B000A; Wed, 11 Mar 2020 23:00:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B8C6D6B000C; Wed, 11 Mar 2020 23:00:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7A7B6B000D; Wed, 11 Mar 2020 23:00:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0052.hostedemail.com [216.40.44.52]) by kanga.kvack.org (Postfix) with ESMTP id 8DB006B000A for ; Wed, 11 Mar 2020 23:00:25 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 82E28181AEF30 for ; Thu, 12 Mar 2020 03:00:25 +0000 (UTC) X-FDA: 76585206810.26.salt55_3abcdd6aa95d X-HE-Tag: salt55_3abcdd6aa95d X-Filterd-Recvd-Size: 2378 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Thu, 12 Mar 2020 03:00:25 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C7AD20735; Thu, 12 Mar 2020 03:00:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583982024; bh=Tzw7OkLhuKwlGaNH6zUaZ92HAbrd6ZAx96ilGAda8sI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=QUV+09ZDscWerAse5sMC/Bzmq/6T1Cul8RokXefoSY9muH4YSLKdP2RTr1DQYA6Un oWCq5rRjXh8iHoFTbisIR8r0um5szGsHkK8yWVdlfMRV9jI4RGxt1tEGYF9CQ01w9F WUozF+mo4X7aT7ET/rDxVpcWQkKMb4sNj7t/6np4= Date: Wed, 11 Mar 2020 20:00:23 -0700 From: Andrew Morton To: Matthew Wilcox Cc: Jules Irenge , boqun.feng@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] backing-dev: refactor wb_congested_put() Message-Id: <20200311200023.974009d9a5648b977d5168f6@linux-foundation.org> In-Reply-To: <20200312022948.GH22433@bombadil.infradead.org> References: <20200312002156.49023-1-jbi.octave@gmail.com> <20200312002156.49023-2-jbi.octave@gmail.com> <20200311175919.30523d55b2e5307ba22bbdc0@linux-foundation.org> <20200312022948.GH22433@bombadil.infradead.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 11 Mar 2020 19:29:48 -0700 Matthew Wilcox wrote: > On Wed, Mar 11, 2020 at 05:59:19PM -0700, Andrew Morton wrote: > > hm, it's hard to get excited over this. Open-coding the > > refcount_dec_and_lock_irqsave() internals at a callsite in order to > > make sparse happy. > > > > Is there some other way, using __acquires (for example)? > > sparse is really bad at conditional lock acquisition. I can well imagine. > we have similar > problems over the vfs. but we shouldn't be obfuscating our code to make > the tool happy. Perhaps sparse needs a way of being directed to suppress checking across a particular function.