Path: csiph.com!news.redatomik.org!aioe.org!bofh.it!news.nic.it!robomod From: Michal Hocko Newsgroups: linux.kernel Subject: Re: [PATCH 2/9] xfs: introduce and use KM_NOLOCKDEP to silence reclaim lockdep false positives Date: Tue, 20 Dec 2016 09:40:02 +0100 Message-ID: References: X-Original-To: Dave Chinner 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=r6k71tyJgWuT0ZyT//fKip+BMN4UK5Qvfm06zTOvx8c=; b=WPJRn12NiZVeAUIJ1OfDC347E4KsxdgnqPsut19ReocaAQGd2pMvkmfJa+dSsbmWY5 BsYtCRpHssM8XafKIuqxVTqxn4PpAuy1IwgZbHN8fnE+vrUCY90RGCbrhDQW8FFLn12e aSiLRANNt95esec/nWfbCtM2U4Hc6nF5irP+L+OMwGOSgAvgvHtKSi5nryLb8ornTHDL /3dcEpgmAsASdHLer3CIYhbnnAnvRm9wVpKNf9kn+c9C0vccX8foPrXt9uPdz/R890W6 QuWc/bAagUdOUphWYhToObPDH/7RTHFL0220MaCmMH9jIGGoU9T9fLra/CQ84/0io0Yk wUOA== X-Gm-Message-State: AIkVDXKnNYQQfujPMHiAoJ0uVhVSj9hqxd7wB0/UWU1Ubs/OakwAMcOGNpDY29z7/HGYEg== X-Received: by 10.28.176.200 with SMTP id z191mr844736wme.17.1482223100161; Tue, 20 Dec 2016 00:38:20 -0800 (PST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.6.0 (2016-04-01) Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 35 Organization: linux.* mail to news gateway X-Original-Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Theodore Ts'o , Chris Mason , David Sterba , Jan Kara , ceph-devel@vger.kernel.org, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, logfs@logfs.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mtd@lists.infradead.org, reiserfs-devel@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, linux-f2fs-devel@lists.sourceforge.net, linux-afs@lists.infradead.org, LKML X-Original-Date: Tue, 20 Dec 2016 09:38:18 +0100 X-Original-Message-ID: <20161220083818.GB3769@dhcp22.suse.cz> X-Original-References: <20161215140715.12732-1-mhocko@kernel.org> <20161215140715.12732-3-mhocko@kernel.org> <20161219212413.GN4326@dastard> X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: csiph.com linux.kernel:1544985 On Tue 20-12-16 08:24:13, Dave Chinner wrote: > On Thu, Dec 15, 2016 at 03:07:08PM +0100, Michal Hocko wrote: > > From: Michal Hocko > > > > Now that the page allocator offers __GFP_NOLOCKDEP let's introduce > > KM_NOLOCKDEP alias for the xfs allocation APIs. While we are at it > > also change KM_NOFS users introduced by b17cb364dbbb ("xfs: fix missing > > KM_NOFS tags to keep lockdep happy") and use the new flag for them > > instead. There is really no reason to make these allocations contexts > > weaker just because of the lockdep which even might not be enabled > > in most cases. > > > > Signed-off-by: Michal Hocko > > I'd suggest that it might be better to drop this patch for now - > it's not necessary for the context flag changeover but does > introduce a risk of regressions if the conversion is wrong. > > Hence I think this is better as a completely separate series > which audits and changes all the unnecessary KM_NOFS allocations > in one go. I've never liked whack-a-mole style changes like this - > do it once, do it properly.... OK, fair enough. I thought it might be better to have an example user so that others can follow but as you say, the risk of regression is really there and these kind of changes definitely need a throughout review. I am not sure I will be able to post more of those changes because that requires an intimate knowledge of the fs so I hope somebody can take over there and follow up. Thanks! -- Michal Hocko SUSE Labs