On 24 Apr 2024, at 18:54, Luis Chamberlain wrote:
> Don't allow to query beyond a mapped file's length. Since this is just
> a debugfs interface allow userspace to be lazy and use a large value so
> we can just use the entire file.
>
> Without this we can end up wasting cycles looking for folios which
> just don't exist for no good reason.
>
> Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> ---
> mm/huge_memory.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 8386d24a163e..86a8c7b3b8dc 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3535,7 +3535,7 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
> struct file *candidate;
> struct address_space *mapping;
> int ret = -EINVAL;
> - pgoff_t index;
> + pgoff_t index, fsize;
> int nr_pages = 1;
> unsigned long total = 0, split = 0;
>
> @@ -3547,11 +3547,14 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
> if (IS_ERR(candidate))
> goto out;
>
> + mapping = candidate->f_mapping;
> + fsize = i_size_read(mapping->host);
> + if (off_end > fsize)
> + off_end = fsize;
> +
> pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
> file_path, off_start, off_end);
>
> - mapping = candidate->f_mapping;
> -
> for (index = off_start; index < off_end; index += nr_pages) {
> struct folio *folio = filemap_get_folio(mapping, index);
LGTM. Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
--
Best Regards,
Yan, Zi
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