[PATCH] mm/page_alloc: Fix try_alloc_pages

Alexei Starovoitov
2025-04-01T03:23:41Z

From: Alexei Starovoitov <ast@kernel.org>

Fix an obvious bug. try_alloc_pages() should set_page_refcounted.

Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

As soon as I fast forwarded and rerun the tests the bug was
seen immediately.
I'm completely baffled how I managed to lose this hunk.
I'm pretty sure I manually tested various code paths of
trylock logic with CONFIG_DEBUG_VM=y.
Pure incompetence :(
Shame.
---
mm/page_alloc.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ffbb5678bc2f..c0bcfe9d0dd9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7248,6 +7248,9 @@ struct page *try_alloc_pages_noprof(int nid, unsigned int order)

/* Unlike regular alloc_pages() there is no __alloc_pages_slowpath(). */

+ if (page)
+ set_page_refcounted(page);
+
if (memcg_kmem_online() && page &&
unlikely(__memcg_kmem_charge_page(page, alloc_gfp, order) != 0)) {
free_pages_nolock(page, order);
--
2.47.1