linux-kernel - Re: [PATCH] mm/memory-failure: fix hardware poison check in unpoison

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Message-ID: <d3e87889-bd00-8b92-0105-80adae8df855@oracle.com>
Date:   Mon, 17 Jul 2023 16:21:54 -0700
From:   Jane Chu <jane.chu@...cle.com>
To:     Sidhartha Kumar <sidhartha.kumar@...cle.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     akpm@...ux-foundation.org, willy@...radead.org,
        linmiaohe@...wei.com, naoya.horiguchi@....com,
        stable@...r.kernel.org
Subject: Re: [PATCH] mm/memory-failure: fix hardware poison check in
 unpoison_memory()

On 7/17/2023 11:18 AM, Sidhartha Kumar wrote:
> It was pointed out[1] that using folio_test_hwpoison() is wrong
> as we need to check the indiviual page that has poison.
> folio_test_hwpoison() only checks the head page so go back to using
> PageHWPoison().
> 
> Reported-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Fixes: a6fddef49eef ("mm/memory-failure: convert unpoison_memory() to folios")
> Cc: stable@...r.kernel.org #v6.4
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
> 
> [1]: https://lore.kernel.org/lkml/ZLIbZygG7LqSI9xe@casper.infradead.org/
> ---
>   mm/memory-failure.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 02b1d8f104d51..a114c8c3039cd 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2523,7 +2523,7 @@ int unpoison_memory(unsigned long pfn)
>   		goto unlock_mutex;
>   	}
>   
> -	if (!folio_test_hwpoison(folio)) {
> +	if (!PageHWPoison(p)) {
>   		unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n",
>   				 pfn, &unpoison_rs);
>   		goto unlock_mutex;

Would it worth the trouble to create folio_page_test_##lname(folio, 
index) macros to address folio subpage?

thanks!
-jane