On 9/25/26 12:41 AM, Yeoreum Yun wrote:
> Since glibc commit 321e1fc73f (“malloc: Enable 2MB THP by default on
> AArch64”),
> glibc may call madvise(MADV_HUGEPAGE) for sufficiently large allocations
> made by memalign().
>
> The underlying VMA may start at a different address from the aligned
> address returned by memalign(). Furthermore, a subsequent
> madvise(MADV_HUGEPAGE) call does not split the VMA because the flag is
> already set.
>
> This causes split_huge_page_test to fail because the check_pmd_huge()
> helpers incorrectly require the address returned by memalign() to
> match the VMA start address reported in /proc/self/smaps.
>
> Instead of relying on /proc/self/smaps, use /proc/self/pagemap and
> /proc/kpageflags to detect huge-page mappings checking PAGE_IS_HUGE
> and PAGE_IS_FILE accroding to type of huge page.
s/accroding/according
>
> Since shmem pages are also file-backed, simply check whether the page
> is file-backed.
>
> Fixes: 642bc52aed9 ("selftests: vm: bring common functions to a new file")
Checkpatch gives a warning saying it requires atleast 12 characters of
commit SHA.
> Suggested-by: David Hildenbrand (Arm) <[email protected]>
> Signed-off-by: Yeoreum Yun <[email protected]>
> ---
[...]
> +static bool __check_pmd_huge(void *addr, size_t len, int nr_hpages,
> + uint64_t hpage_size, enum check_huge_type type)
> +{
> + int pagemap_fd;
> + int nr_pmd_mappings = 0;
> + uint64_t categories;
> + char *start = addr;
> + char *end = start + len;
> +
> + pagemap_fd = open(PAGEMAP_PATH, O_RDONLY);
> + if (pagemap_fd < 0)
> + ksft_exit_fail_msg("open pagemap fail\n");
Can we use ksft_exit_fail_perror("open pagemap") here? Will help in
diagnosing failures as well.
Apart from these nits, rest looks good.
Reviewed-by: Sarthak Sharma <[email protected]>
