On 24 Apr 2024, at 18:57, Luis Chamberlain wrote:
> We should check as early as possible if we should bail due to writeback
> or truncation. This will allow us to add further sanity checks earlier
> as well.
>
> This introduces no functional changes.
>
> Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> ---
> mm/huge_memory.c | 23 +++++++++++------------
> 1 file changed, 11 insertions(+), 12 deletions(-)
>
> While working on min order support for LBS this came up as an improvement
> as we can check for the min order early earlier, so this sets the stage
> up for that.
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 86a8c7b3b8dc..32c701821e0d 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3055,8 +3055,17 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
> if (new_order >= folio_order(folio))
> return -EINVAL;
>
> - /* Cannot split anonymous THP to order-1 */
> - if (new_order == 1 && folio_test_anon(folio)) {
> + if (folio_test_writeback(folio))
> + return -EBUSY;
> +
> + if (!folio_test_anon(folio)) {
> + /* Truncated ? */
> + if (!folio->mapping) {
> + ret = -EBUSY;
> + goto out;
> + }
> + } else if (new_order == 1) {
> + /* Cannot split anonymous THP to order-1 */
> VM_WARN_ONCE(1, "Cannot split to order-1 folio");
> return -EINVAL;
> }
> @@ -3079,16 +3088,12 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
> }
> }
>
> -
> is_hzp = is_huge_zero_page(&folio->page);
> if (is_hzp) {
> pr_warn_ratelimited("Called split_huge_page for huge zero page\n");
> return -EBUSY;
> }
>
> - if (folio_test_writeback(folio))
> - return -EBUSY;
> -
> if (folio_test_anon(folio)) {
> /*
> * The caller does not necessarily hold an mmap_lock that would
> @@ -3111,12 +3116,6 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
>
> mapping = folio->mapping;
>
> - /* Truncated ? */
> - if (!mapping) {
> - ret = -EBUSY;
> - goto out;
> - }
> -
> /*
> * Do not split if mapping has minimum folio order
> * requirement.
> --
> 2.43.0
LGTM. Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
--
Best Regards,
Yan, Zi
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