From: Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH 2/9] xfs: introduce and use KM_NOLOCKDEP to silence
 reclaim lockdep false positives
Date: Tue, 20 Dec 2016 08:24:13 +1100
Message-ID: <20161219212413.GN4326@dastard>
References: <20161215140715.12732-1-mhocko@kernel.org>
 <20161215140715.12732-3-mhocko@kernel.org>
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Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Theodore Ts'o <tytso@mit.edu>, Chris Mason <clm@fb.com>,
	David Sterba <dsterba@suse.cz>, Jan Kara <jack@suse.cz>,
	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 <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
To: Michal Hocko <mhocko@kernel.org>
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On Thu, Dec 15, 2016 at 03:07:08PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 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 <mhocko@suse.com>

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....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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