[PATCH 6.12 252/460] mm/page_alloc: forward the gfp flags from alloc_contig_range() to post_alloc_hook()

Greg Kroah-Hartman
2026-03-23T14:41:51Z

6.12-stable review patch. If anyone has any objections, please let me know.

------------------

From: David Hildenbrand <david@redhat.com>

[ Upstream commit 7b755570064fcb9cde37afd48f6bc65151097ba7 ]

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.

Link: https://lkml.kernel.org/r/20241203094732.200195-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: d155aab90fff ("mm/kfence: fix KASAN hardware tag faults during late enablement")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/page_alloc.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6579,7 +6579,7 @@ int __alloc_contig_migrate_range(struct
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;

@@ -6590,7 +6590,7 @@ static void split_free_pages(struct 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;
@@ -6608,7 +6608,8 @@ static void split_free_pages(struct 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;

/*
@@ -6756,7 +6757,7 @@ int alloc_contig_range_noprof(unsigned l
}

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)