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Date:   Wed, 5 Apr 2023 08:04:56 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     David Howells <dhowells@redhat.com>
Cc:     Matthew Wilcox <willy@infradead.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
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        Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, Jeff Layton <jlayton@kernel.org>,
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        Lorenzo Bianconi <lorenzo@kernel.org>,
        Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
        Sean Wang <sean.wang@mediatek.com>,
        Mark Lee <Mark-MC.Lee@mediatek.com>,
        Keith Busch <kbusch@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        linux-nvme@lists.infradead.org, linux-mediatek@lists.infradead.org
Subject: Re: [PATCH v3 06/55] mm: Make the page_frag_cache allocator use
 per-cpu
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On Fri, Mar 31, 2023 at 05:08:25PM +0100, David Howells wrote:
> Make the page_frag_cache allocator have a separate allocation bucket for
> each cpu to avoid racing.  This means that no lock is required, other than
> preempt disablement, to allocate from it, though if a softirq wants to
> access it, then softirq disablement will need to be added.

Can you split this into a separte series?  Right now I only see this
patch in mbox and miss the context on why wed want this.

> Make the NVMe and mediatek drivers pass in NULL to page_frag_cache() and
> use the default allocation buckets rather than defining their own.

Can you explain why?