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From: Pankaj Raghav <p.raghav@samsung.com>
To: donettom@linux.ibm.com
Cc: akpm@linux-foundation.org,
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	linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH] selftest: mm: Test if hugepage does not get leaked during __bio_release_pages()
Date: Thu,  6 Jun 2024 13:14:29 +0000
Message-ID: <20240606131436.592793-1-p.raghav@samsung.com>
In-Reply-To: <20240604132801.23377-1-donettom@linux.ibm.com>
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> +void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off)
> +{
> +	int fd;
> +	char *buffer =  NULL;
> +	char *orig_buffer = NULL;
> +	size_t h_pagesize = 0;
> +	size_t writesize;
> +	int free_hpage_b = 0;
> +	int free_hpage_a = 0;
> +
> +	writesize = end_off - start_off;
> +
> +	/* Get the default huge page size */
> +	h_pagesize = default_huge_page_size();
> +	if (!h_pagesize)
> +		ksft_exit_fail_msg("Unable to determine huge page size\n");
> +
> +	/* Open the file to DIO */
> +	fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT);

I encountered a build error as follows in NixOS:

In file included from /nix/store/fwh4fxd747m0py3ib3s5abamia9nrf90-glibc-2.39-52-dev/include/fcntl.h:342,
                 from hugetlb_dio.c:15:
In function ‘open’,
    inlined from ‘run_dio_using_hugetlb’ at hugetlb_dio.c:41:7:
/nix/store/fwh4fxd747m0py3ib3s5abamia9nrf90-glibc-2.39-52-dev/include/bits/fcntl2.h:50:11: error: call to ‘__open_missing_mode’ declared with attribute error: open with O_CREAT or O_TMPFILE in second argument needs 3 arguments
   50 |           __open_missing_mode ();


I saw a commit that fixed similar issues with open syscall before:
8b65ef5ad486 ("selftests/mm: Fix build with _FORTIFY_SOURCE")

So something like this should fix the issue?

-       fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT);
+       fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664);

> +	if (fd < 0)
> +		ksft_exit_fail_msg("Error opening file");
> +