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Date:   Tue, 24 Sep 2019 13:51:33 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     cl@linux.com
Cc:     "Darrick J. Wong" <darrick.wong@oracle.com>, dsterba@suse.cz,
        Vlastimil Babka <vbabka@suse.cz>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Ming Lei <ming.lei@redhat.com>,
        Dave Chinner <david@fromorbit.com>,
        Christoph Hellwig <hch@lst.de>, linux-xfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        linux-btrfs@vger.kernel.org, Roman Gushchin <guro@fb.com>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for
 kmalloc(power-of-two)
Message-ID: <20190924205133.GK1855@bombadil.infradead.org>
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On Tue, Sep 24, 2019 at 08:47:52PM +0000, cl@linux.com wrote:
> On Mon, 23 Sep 2019, Darrick J. Wong wrote:
> 
> > On Mon, Sep 23, 2019 at 07:17:10PM +0200, David Sterba wrote:
> > > On Mon, Sep 23, 2019 at 06:36:32PM +0200, Vlastimil Babka wrote:
> > > > So if anyone thinks this is a good idea, please express it (preferably
> > > > in a formal way such as Acked-by), otherwise it seems the patch will be
> > > > dropped (due to a private NACK, apparently).
> >
> > Oh, I didn't realize  ^^^^^^^^^^^^ that *some* of us are allowed the
> > privilege of gutting a patch via private NAK without any of that open
> > development discussion incovenience. <grumble>
> 
> There was a public discussion about this issue and from what I can tell
> the outcome was that the allocator already provides what you want. Which
> was a mechanism to misalign objects and detect these issues. This
> mechanism has been in use for over a decade.

You missed the important part, which was *ENABLED BY DEFAULT*.  People
who are enabling a debugging option to debug their issues, should not
have to first debug all the other issues that enabling that debugging
option uncovers!