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Date:   Sat, 20 Mar 2021 09:32:49 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Minchan Kim <minchan@kernel.org>
Cc:     linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
        joaodias@google.com, surenb@google.com, cgoldswo@codeaurora.org,
        willy@infradead.org, mhocko@suse.com, david@redhat.com,
        vbabka@suse.cz, linux-fsdevel@vger.kernel.org,
        oliver.sang@intel.com
Subject: Re: [PATCH v4 3/3] mm: fs: Invalidate BH LRU during page migration
Message-Id: <20210320093249.2df740cd139449312211c452@linux-foundation.org>
In-Reply-To: <20210319175127.886124-3-minchan@kernel.org>
References: <20210319175127.886124-1-minchan@kernel.org>
        <20210319175127.886124-3-minchan@kernel.org>
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On Fri, 19 Mar 2021 10:51:27 -0700 Minchan Kim <minchan@kernel.org> wrote:

> Pages containing buffer_heads that are in one of the per-CPU
> buffer_head LRU caches will be pinned and thus cannot be migrated.
> This can prevent CMA allocations from succeeding, which are often used
> on platforms with co-processors (such as a DSP) that can only use
> physically contiguous memory. It can also prevent memory
> hot-unplugging from succeeding, which involves migrating at least
> MIN_MEMORY_BLOCK_SIZE bytes of memory, which ranges from 8 MiB to 1
> GiB based on the architecture in use.
> 
> Correspondingly, invalidate the BH LRU caches before a migration
> starts and stop any buffer_head from being cached in the LRU caches,
> until migration has finished.
> 
> Tested-by: Oliver Sang <oliver.sang@intel.com>
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Signed-off-by: Chris Goldsworthy <cgoldswo@codeaurora.org>
> Signed-off-by: Minchan Kim <minchan@kernel.org>

The signoff chain ordering might mean that Chris was the primary author, but
there is no From:him.  Please clarify?