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From: Matthew Wilcox <willy@infradead.org>
To: Stefan Roesch <shr@devkernel.io>
Cc: kernel-team@fb.com, akpm@linux-foundation.org,
	hannes@cmpxchg.org, riel@surriel.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v3] mm: Fix for negative counter: nr_file_hugepages
Date: Wed, 8 Nov 2023 17:29:51 +0000	[thread overview]
Message-ID: <ZUvFjzqTXg3WU2Q6@casper.infradead.org> (raw)
In-Reply-To: <20231108171517.2436103-1-shr@devkernel.io>

On Wed, Nov 08, 2023 at 09:15:17AM -0800, Stefan Roesch wrote:
> While qualifiying the 6.4 release, the following warning was detected in
> messages:
> 
> vmstat_refresh: nr_file_hugepages -15664
> 
> The warning is caused by the incorrect updating of the NR_FILE_THPS
> counter in the function split_huge_page_to_list. The if case is checking
> for folio_test_swapbacked, but the else case is missing the check for
> folio_test_pmd_mappable. The other functions that manipulate the counter
> like __filemap_add_folio and filemap_unaccount_folio have the
> corresponding check.
> 
> I have a test case, which reproduces the problem. It can be found here:
>   https://github.com/sroeschus/testcase/blob/main/vmstat_refresh/madv.c
> 
> The test case reproduces on an XFS filesystem. Running the same test
> case on a BTRFS filesystem does not reproduce the problem.
> 
> AFAIK version 6.1 until 6.6 are affected by this problem.
> 
> Signed-off-by: Stefan Roesch <shr@devkernel.io>
> Co-debugged-by: Johannes Weiner <hannes@cmpxchg.org>
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Cc: stable@vger.kernel.org

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>


  reply	other threads:[~2023-11-08 17:30 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-08 17:15 Stefan Roesch
2023-11-08 17:29 ` Matthew Wilcox [this message]
2023-11-08 17:38 ` David Hildenbrand
2023-11-14  1:42 ` Yang Shi

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