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Date:   Fri, 10 Jun 2022 14:56:05 -0700
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Subject: Re: [PATCH 06/10] hugetlbfs: Convert remove_inode_hugepages() to use
 filemap_get_folios()
Content-Language: en-US
To:     Matthew Wilcox <willy@infradead.org>,
        Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc:     linux-ext4@vger.kernel.org, gerald.schaefer@linux.ibm.com,
        gor@linux.ibm.com, agordeev@linux.ibm.com,
        linux-f2fs-devel@lists.sourceforge.net,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-nilfs@vger.kernel.org
References: <20220605193854.2371230-7-willy@infradead.org>
 <20220610155205.3111213-1-sumanthk@linux.ibm.com>
 <YqO08Dsq8ZcAcWDQ@casper.infradead.org>
From:   Mike Kravetz <mike.kravetz@oracle.com>
In-Reply-To: <YqO08Dsq8ZcAcWDQ@casper.infradead.org>
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On 6/10/22 14:17, Matthew Wilcox wrote:
> On Fri, Jun 10, 2022 at 05:52:05PM +0200, Sumanth Korikkar wrote:
>> To reproduce:
>> * clone libhugetlbfs:
>> * Execute, PATH=$PATH:"obj64/" LD_LIBRARY_PATH=../obj64/ alloc-instantiate-race shared
> 
> ... it's a lot harder to set up hugetlb than that ...
> 
> anyway, i figured it out without being able to run the reproducer.
> 
> Can you try this?

I can confirm that libhugetlbfs tests do not trigger the BUG with the
below change.
-- 
Mike Kravetz

> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index a30587f2e598..8ef861297ffb 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2160,7 +2160,11 @@ unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
>  		if (xa_is_value(folio))
>  			continue;
>  		if (!folio_batch_add(fbatch, folio)) {
> -			*start = folio->index + folio_nr_pages(folio);
> +			unsigned long nr = folio_nr_pages(folio);
> +
> +			if (folio_test_hugetlb(folio))
> +				nr = 1;
> +			*start = folio->index + nr;
>  			goto out;
>  		}
>  	}
>