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Date:   Fri, 26 May 2023 17:57:36 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     David Howells <dhowells@redhat.com>
Cc:     netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
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        David Ahern <dsahern@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Jeroen de Borst <jeroendb@google.com>,
        Catherine Sullivan <csully@google.com>,
        Shailend Chand <shailend@google.com>,
        Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
        Sean Wang <sean.wang@mediatek.com>,
        Mark Lee <Mark-MC.Lee@mediatek.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-nvme@lists.infradead.org,
        Alexander Duyck <alexander.duyck@gmail.com>
Subject: Re: [PATCH net-next 05/12] mm: Make the page_frag_cache allocator
 handle __GFP_ZERO itself
Message-ID: <20230526175736.7e75dcf9@kernel.org>
In-Reply-To: <20230524153311.3625329-6-dhowells@redhat.com>
References: <20230524153311.3625329-1-dhowells@redhat.com>
        <20230524153311.3625329-6-dhowells@redhat.com>
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On Wed, 24 May 2023 16:33:04 +0100 David Howells wrote:
> Make the page_frag_cache allocator handle __GFP_ZERO itself rather than
> passing it off to the page allocator.  There may be a mix of callers, some
> specifying __GFP_ZERO and some not - and even if all specify __GFP_ZERO, we
> might refurbish the page, in which case the returned memory doesn't get
> cleared.

I think it's pretty clear that page frag allocator was never supposed
to support GFP_ZERO, as we don't need it in networking.. So maybe
you're better off adding the memset() in nvme?

CCing Alex, who I think would say something along those lines :)
IDK how much we still care given that most networking drivers are
migrating to page_poll these days.