Re: [LTP] hugetlb/hugefallocate: Add hugefallocate03 to stress test fallocate on hugetlbfs

[linuxtestproject.agent@gmail.com]

Hi Pavithra,

On Sat Sep 19 23:19:20 2026 +0530, Pavithra <pavrampu@linux.ibm.com> wrote:
> hugetlb/hugefallocate: Add hugefallocate03 to stress test fallocate on hugetlbfs

> +/*\
> + * Stress test fallocate. This test starts three threads.
> + * Thread one will continually punch/fill holes via falloc.
> + * Thread two will continually fault in those same pages.
> + * Thread three will continually mmap/munmap that page range.
> + */

Format syscall names using the `:manpage:` role (e.g.
`:manpage:`fallocate(2)``, `:manpage:`mmap(2)``, `:manpage:`munmap(2)``)
and avoid abbreviations like "falloc". Document why root privileges are
required (.needs_root = 1).

> +	while (1) {
> +		tpage = ((long long)random()) % (max_hpages);
> +		pthread_mutex_lock(&fault_addr_lock);
> +		foo = *((char *)(fault_mmap_addr + (tpage * hpage_size)));
> +		*((char *)(fault_mmap_addr + (tpage * hpage_size))) = foo;
> +		pthread_mutex_unlock(&fault_addr_lock);
> +
> +		nanosleep(&ts, NULL); /* thread cancellation point */
> +	}

fault_addr_lock is not accessed by any other thread and can be removed.
Cast to volatile char * when writing back to prevent the compiler from
optimizing out the write. Replace nanosleep(&ts, NULL) with
pthread_testcancel() for thread cancellation.

> +	while (1) {
> +		pthread_mutex_lock(&mmap_munmap_lock);
> +		mmap_munmap_addr = SAFE_MMAP(NULL, max_hpages * hpage_size,
> +				PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
> +		SAFE_MUNMAP(mmap_munmap_addr, max_hpages * hpage_size);
> +		mmap_munmap_addr = NULL;
> +		pthread_mutex_unlock(&mmap_munmap_lock);
> +
> +		nanosleep(&ts, NULL);   /* thread cancellation point */
> +	}

mmap_munmap_lock is unnecessary since no other thread accesses this
address; mmap_munmap_addr can be a local variable. Replace
nanosleep(&ts, NULL) with pthread_testcancel().

> +	unsigned int seed = (int)getpid() * time(NULL);
> +
> +	srandom(seed);
> +	tst_res(TINFO, "Seed = %d", seed);

seed is unsigned int; use %u instead of %d.

> +	/* First preallocate file with max_hpages pages */
> +	err = fallocate(fd, 0, 0, hpage_size * max_hpages);
> +	if (err) {
> +		if (errno == EOPNOTSUPP)
> +			tst_brk(TCONF, "fallocate() Operation is not supported");
> +		tst_res(TFAIL | TERRNO, "fallocate():");
> +		goto windup;
> +	}
> +
> +	free_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
> +	if (free_before - free_after != max_hpages) {
> +		tst_res(TFAIL, "fallocate did not preallocate %ld huge pages",
> +				max_hpages);
> +		goto windup;
> +	}

If fallocate or preallocation fails, branching to windup causes the test
to report TPASS in the subsequent check because SAFE_CLOSE(fd) restores
the free counts and thread_err remains 0. Use tst_brk(TBROK | TERRNO, ...)
to abort on preallocation failure. Also use %lu instead of %ld for
max_hpages.

> +windup:
> +	SAFE_CLOSE(fd);
> +
> +	free_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
> +	rsvd_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
> +
> +	if (thread_err)
> +		tst_res(TFAIL, "fallocate() failed during stress, see above");
> +	else if (free_after != free_before || rsvd_after != rsvd_before)
> +		tst_res(TFAIL, "free or reserve counts incorrect after fallocate stress test");
> +	else
> +		tst_res(TPASS, "fallocate stress test passed");

Use TST_EXP_EQ_LU(free_after, free_before) and
TST_EXP_EQ_LU(rsvd_after, rsvd_before) to report free and reserve count
comparisons.

> +static void cleanup(void)
> +{
> +	if (fd >= 0)
> +		SAFE_CLOSE(fd);
> +}

Use if (fd != -1) instead of if (fd >= 0).

Verdict - Needs revision

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LTP AI Reviewer

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