linux-kernel - Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two)

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Message-ID: <20190923171710.GN2751@twin.jikos.cz>
Date:   Mon, 23 Sep 2019 19:17:10 +0200
From:   David Sterba <dsterba@...e.cz>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Ming Lei <ming.lei@...hat.com>,
        Dave Chinner <david@...morbit.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Christoph Hellwig <hch@....de>, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        linux-btrfs@...r.kernel.org, Roman Gushchin <guro@...com>,
        Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for
 kmalloc(power-of-two)

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).

As a user of the allocator interface in filesystem, I'd like to see a
more generic way to address the alignment guarantees so we don't have to
apply workarounds like 3acd48507dc43eeeb each time we find that we
missed something. (Where 'missed' might be another sort of weird memory
corruption hard to trigger.)

The workaround got applied because I was not sure about the timeframe of
merge of this patch, also to remove pressure for merge in case there are
more private acks and nacks to be sent. In the end I'd be fine with
reverting the workaround in order to use the generic code again.

Thanks.