linux-kernel - Re: [PATCH 2/2] mm: shmem: improve the tmpfs large folio read performance

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Message-ID: <Zw_d0EVAJkpNJEbA@casper.infradead.org>
Date: Wed, 16 Oct 2024 16:37:52 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: akpm@...ux-foundation.org, hughd@...gle.com, david@...hat.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mm: shmem: improve the tmpfs large folio read
 performance

On Wed, Oct 16, 2024 at 06:09:30PM +0800, Baolin Wang wrote:
> @@ -3128,8 +3127,9 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
>  		if (folio) {
>  			folio_unlock(folio);
>  
> -			page = folio_file_page(folio, index);
> -			if (PageHWPoison(page)) {
> +			if (folio_test_hwpoison(folio) ||
> +			    (folio_test_large(folio) &&
> +			     folio_test_has_hwpoisoned(folio))) {

Hm, so if we have hwpoison set on one page in a folio, we now can't read
bytes from any page in the folio?  That seems like we've made a bad
situation worse.