Re: [LTP] [PATCH v2 3/5] Hugetlb: Migrating libhugetlbfs fadvise_reserve

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> +/*\
> + * [Description]
> + *
> + * fadvise() on some kernels can cause the reservation counter to get
> + * corrupted. The problem is that the patches are allocated for the
> + * reservation but not faulted in at the time of allocation. The counters
> + * do not get updated and effectively "leak". This test identifies whether
> + * the kernel is vulnerable to the problem or not. It's fixed in kernel
> + * by commit f2deae9d4e70793568ef9e85d227abb7bef5b622.
> + */
> +
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <sys/mount.h>
> +#include <limits.h>
> +#include <sys/param.h>
> +#include <sys/types.h>
> +
> +#include "hugetlb.h"
> +
> +#define MNTPOINT "hugetlbfs/"
> +static long hpage_size;
> +static int  fd = -1;
> +
> +static void run_test(void)
> +{
> +	void *p;
> +	unsigned long initial_rsvd, map_rsvd, fadvise_rsvd, end_rsvd;
> +
> +	fd = tst_creat_unlinked(MNTPOINT);
> +
> +	initial_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
> +	tst_res(TINFO, "Reserve count before map: %lu", initial_rsvd);
> +
> +	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
> +		 fd, 0);
> +	map_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
> +	tst_res(TINFO, "Reserve count after map: %lu", map_rsvd);
> +
> +	if (posix_fadvise(fd, 0, hpage_size, POSIX_FADV_WILLNEED) == -1) {
> +		tst_res(TFAIL|TERRNO, "fadvise()");
> +		goto cleanup;
> +	}

If we follow how SAFE_MACROS() works this should rather be:

	if (posix_fadvise(...)
		tst_brk(TBROK|TERRNO, "fadvise()");

> +	fadvise_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
> +	tst_res(TINFO, "Reserve count after fadvise: %lu", fadvise_rsvd);
> +
> +	memset(p, 1, hpage_size);
> +
> +	SAFE_MUNMAP(p, hpage_size);
> +	p = NULL;
> +	SAFE_CLOSE(fd);
> +	end_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
> +	tst_res(TINFO, "Reserve count after close: %lu", end_rsvd);
> +
> +	TST_EXP_EQ_LU(end_rsvd, initial_rsvd);
> +cleanup:
> +	if (p)
> +		SAFE_MUNMAP(p, hpage_size);
> +	if (fd > 0)
> +		SAFE_CLOSE(fd);
> +}
> +
> +static void setup(void)
> +{
> +	hpage_size = SAFE_READ_MEMINFO(MEMINFO_HPAGE_SIZE)*1024;
> +}
> +
> +static void cleanup(void)
> +{
> +	if (fd > 0)
> +		SAFE_CLOSE(fd);
> +}
> +
> +static struct tst_test test = {
> +	.tags = (struct tst_tag[]) {
> +		{"linux-git", "f2deae9d4e70793568ef9e85d227abb7bef5b622"},

We usually shorten the hash to first 12 characters however things should
work fine either way.

> +		{}
> +	},
> +	.needs_root = 1,
> +	.mntpoint = MNTPOINT,
> +	.needs_hugetlbfs = 1,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.test_all = run_test,
> +	.hugepages = {1, TST_NEEDS},
> +};
> -- 
> 2.31.1
> 

-- 
Cyril Hrubis
chrubis@suse.cz

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