linux-kernel - Re: [PATCH v7 3/8] mm: factor helpers for memory_failure_dev

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Date:   Thu, 14 Oct 2021 23:33:22 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Shiyang Ruan <ruansy.fnst@...itsu.com>
Cc:     linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, djwong@...nel.org,
        dan.j.williams@...el.com, david@...morbit.com, hch@...radead.org,
        jane.chu@...cle.com
Subject: Re: [PATCH v7 3/8] mm: factor helpers for memory_failure_dev_pagemap

On Fri, Sep 24, 2021 at 09:09:54PM +0800, Shiyang Ruan wrote:
> memory_failure_dev_pagemap code is a bit complex before introduce RMAP
> feature for fsdax.  So it is needed to factor some helper functions to
> simplify these code.
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
> ---
>  mm/memory-failure.c | 140 ++++++++++++++++++++++++--------------------
>  1 file changed, 76 insertions(+), 64 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 54879c339024..8ff9b52823c0 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1430,6 +1430,79 @@ static int try_to_split_thp_page(struct page *page, const char *msg)
>  	return 0;
>  }
>  
> +static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
> +		struct address_space *mapping, pgoff_t index, int flags)
> +{
> +	struct to_kill *tk;
> +	unsigned long size = 0;
> +
> +	list_for_each_entry(tk, to_kill, nd)
> +		if (tk->size_shift)
> +			size = max(size, 1UL << tk->size_shift);
> +	if (size) {

Nit: an empty line here would be nice for readability.

> +	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
> +		/*
> +		 * TODO: Handle HMM pages which may need coordination
> +		 * with device-side memory.
> +		 */
> +		return -EBUSY;

We've got rid of the HMM terminology for device private memory, so
I'd reword this update the comment to follow that while you're at it.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@....de>