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From: Matthew Wilcox <willy@infradead.org>
To: Alistair Popple <apopple@nvidia.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org, jack@suse.cz,
	david@fromorbit.com, jhubbard@nvidia.com
Subject: Re: [PATCH] mm: Fix serialization adding transparent huge pages to page cache
Date: Mon, 20 Jun 2022 14:56:39 +0100	[thread overview]
Message-ID: <YrB8l9KfeUgvHtUU@casper.infradead.org> (raw)
In-Reply-To: <20220620090536.1474002-1-apopple@nvidia.com>

On Mon, Jun 20, 2022 at 07:05:36PM +1000, Alistair Popple wrote:
> Commit 793917d997df ("mm/readahead: Add large folio readahead")
> introduced support for using large folios for filebacked pages if the
> filesystem supports it.
> 
> page_cache_ra_order() was introduced to allocate and add these large
> folios to the page cache. However adding pages to the page cache should
> be serialized against truncation and hole punching by taking
> invalidate_lock. Not doing so can lead to data races resulting in stale
> data getting added to the page cache and marked up-to-date. See commit
> 730633f0b7f9 ("mm: Protect operations adding pages to page cache with
> invalidate_lock") for more details.
> 
> This issue was found by inspection but a testcase revealed it was
> possible to observe in practice on XFS. Fix this by taking
> invalidate_lock in page_cache_ra_order(), to mirror what is done for the
> non-thp case in page_cache_ra_unbounded().

Thanks, added to pagecache:for-next and I'll be including it as part of
the pull request for -rc4.


      parent reply	other threads:[~2022-06-20 13:56 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-20  9:05 Alistair Popple
2022-06-20  9:57 ` Jan Kara
2022-06-20 13:56 ` Matthew Wilcox [this message]

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