linux-kernel - Re: [PATCH] mm: memory-failure: cleanup try_to_split_thp

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Date:   Thu, 4 Aug 2022 00:45:56 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
CC:     Miaohe Lin <linmiaohe@...wei.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: memory-failure: cleanup try_to_split_thp_page()

On Tue, Aug 02, 2022 at 10:12:56AM +0800, Kefeng Wang wrote:
> Since commit 5d1fd5dc877b ("mm,hwpoison: introduce MF_MSG_UNSPLIT_THP"),
> the action_result() called to show memory error event in memory_failure(),
> so the pr_info() in try_to_split_thp_page() is only needed in
> soft_offline_in_use_page().
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>

Thanks, looks good to me.  Probably this patch may come before
"mm: memory-failure: convert to pr_fmt()" to be a cleanup.

And recently another patch [1] is trying to change the same function, so we
might need to resolve the conflict with it.  I expect it's not so hard, but
I think your series had better come after [1] because [1] is a bug fix and
might be backported to stable-5.19.

[1] https://lore.kernel.org/linux-mm/20220803025243.155798-1-fengwei.yin@intel.com/T/#u

Thanks,
Naoya Horiguchi

> ---
>  mm/memory-failure.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index f0e1961d4482..59633a617a0a 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1524,20 +1524,18 @@ static int identify_page_state(unsigned long pfn, struct page *p,
>  	return page_action(ps, p, pfn);
>  }
>  
> -static int try_to_split_thp_page(struct page *page, const char *msg)
> +static int try_to_split_thp_page(struct page *page)
>  {
> +	int ret;
> +
>  	lock_page(page);
> -	if (unlikely(split_huge_page(page))) {
> -		unsigned long pfn = page_to_pfn(page);
> +	ret = split_huge_page(page);
> +	unlock_page(page);
>  
> -		unlock_page(page);
> -		pr_info("%s: %#lx: thp split failed\n", msg, pfn);
> +	if (unlikely(ret))
>  		put_page(page);
> -		return -EBUSY;
> -	}
> -	unlock_page(page);
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
> @@ -2079,7 +2077,7 @@ int memory_failure(unsigned long pfn, int flags)
>  		 * page is a valid handlable page.
>  		 */
>  		SetPageHasHWPoisoned(hpage);
> -		if (try_to_split_thp_page(p, "Memory Failure") < 0) {
> +		if (try_to_split_thp_page(p) < 0) {
>  			action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
>  			res = -EBUSY;
>  			goto unlock_mutex;
> @@ -2503,8 +2501,11 @@ static int soft_offline_in_use_page(struct page *page)
>  	struct page *hpage = compound_head(page);
>  
>  	if (!PageHuge(page) && PageTransHuge(hpage))
> -		if (try_to_split_thp_page(page, "soft offline") < 0)
> +		if (try_to_split_thp_page(page) < 0) {
> +			pr_info("soft offline: %#lx: thp split failed\n",
> +				page_to_pfn(page));
>  			return -EBUSY;
> +		}
>  	return __soft_offline_page(page);
>  }
>  
> -- 
> 2.35.3