On 12/3/24 10:47, David Hildenbrand wrote:
> In the __GFP_COMP case, we already pass the gfp_flags to
> prep_new_page()->post_alloc_hook(). However, in the !__GFP_COMP case, we
> essentially pass only hardcoded __GFP_MOVABLE to post_alloc_hook(),
> preventing some action modifiers from being effective..
>
> Let's pass our now properly adjusted gfp flags there as well.
>
> This way, we can now support __GFP_ZERO for alloc_contig_*().
>
> As a side effect, we now also support __GFP_SKIP_ZERO and__GFP_ZEROTAGS;
> but we'll keep the more special stuff (KASAN, NOLOCKDEP) disabled for
> now.
>
> It's worth noting that with __GFP_ZERO, we might unnecessarily zero pages
> when we have to release part of our range using free_contig_range() again.
> This can be optimized in the future, if ever required; the caller we'll
> be converting (powernv/memtrace) next won't trigger this.
>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> mm/page_alloc.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 54594cc4f650..71d70bc0ad79 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6364,7 +6364,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
> return (ret < 0) ? ret : 0;
> }
>
> -static void split_free_pages(struct list_head *list)
> +static void split_free_pages(struct list_head *list, gfp_t gfp_mask)
> {
> int order;
>
> @@ -6375,7 +6375,7 @@ static void split_free_pages(struct list_head *list)
> list_for_each_entry_safe(page, next, &list[order], lru) {
> int i;
>
> - post_alloc_hook(page, order, __GFP_MOVABLE);
> + post_alloc_hook(page, order, gfp_mask);
> set_page_refcounted(page);
> if (!order)
> continue;
> @@ -6393,7 +6393,8 @@ static void split_free_pages(struct list_head *list)
> static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask)
> {
> const gfp_t reclaim_mask = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
> - const gfp_t action_mask = __GFP_COMP | __GFP_RETRY_MAYFAIL | __GFP_NOWARN;
> + const gfp_t action_mask = __GFP_COMP | __GFP_RETRY_MAYFAIL | __GFP_NOWARN |
> + __GFP_ZERO | __GFP_ZEROTAGS | __GFP_SKIP_ZERO;
> const gfp_t cc_action_mask = __GFP_RETRY_MAYFAIL | __GFP_NOWARN;
>
> /*
> @@ -6541,7 +6542,7 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end,
> }
>
> if (!(gfp_mask & __GFP_COMP)) {
> - split_free_pages(cc.freepages);
> + split_free_pages(cc.freepages, gfp_mask);
>
> /* Free head and tail (if any) */
> if (start != outer_start)
