linux-kernel - Re: [PATCH v4 1/2] mm/memory-failure.c: avoid calling invalidate_inode

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Message-ID: <YjYC1XaeDPosSIDa@casper.infradead.org>
Date:   Sat, 19 Mar 2022 16:20:37 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, naoya.horiguchi@....com,
        shy828301@...il.com, mike.kravetz@...cle.com, david@...hat.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] mm/memory-failure.c: avoid calling
 invalidate_inode_page() with unexpected pages

On Sun, Mar 20, 2022 at 01:13:33PM +0800, Miaohe Lin wrote:
> invalidate_inode_page() can invalidate the pages in the swap cache because
> the check of page->mapping != mapping is removed via Matthew's patch titled
> "mm/truncate: Inline invalidate_complete_page() into its one caller". But
> invalidate_inode_page() is not expected to deal with the pages in the swap
> cache. Also non-lru movable page can reach here too. They're not page cache
> pages. Skip these pages by checking PageSwapCache and PageLRU to fix this
> unexpected issue.

I disagree with this changelog.

invalidate_inode_page() should not be called for pages which are not
in the page cache.

And then the patch shouldn't test PageLRU (which is actually wrong) or
PageSwapCache().  It should simply be:

+	if (!PageHuge(page) && !PageAnon(page))

> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
>  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 5444a8ef4867..ecf45961f3b6 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2178,7 +2178,7 @@ static int __soft_offline_page(struct page *page)
>  		return 0;
>  	}
>  
> -	if (!PageHuge(page))
> +	if (!PageHuge(page) && PageLRU(page) && !PageSwapCache(page))
>  		/*
>  		 * Try to invalidate first. This should work for
>  		 * non dirty unmapped page cache pages.
> -- 
> 2.23.0
> 
>