[PATCH net-next v2] page_pool: always add GFP_NOWARN for ATOMIC allocations

[Jakub Kicinski <kuba@kernel.org>]

Driver authors often forget to add GFP_NOWARN for page allocation
from the datapath. This is annoying to users as OOMs are a fact
of life, and we pretty much expect network Rx to hit page allocation
failures during OOM. Make page pool add GFP_NOWARN for ATOMIC allocations
by default.

Reviewed-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
v2:
 - drop the micro-optimization
v1: https://lore.kernel.org/20250908152123.97829-1-kuba@kernel.org

CC: hawk@kernel.org
CC: ilias.apalodimas@linaro.org
---
 net/core/page_pool.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index ba70569bd4b0..36a98f2bcac3 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -555,6 +555,12 @@ static noinline netmem_ref __page_pool_alloc_netmems_slow(struct page_pool *pool
 	netmem_ref netmem;
 	int i, nr_pages;
 
+	/* Unconditionally set NOWARN if allocating from NAPI.
+	 * Drivers forget to set it, and OOM reports on packet Rx are useless.
+	 */
+	if ((gfp & GFP_ATOMIC) == GFP_ATOMIC)
+		gfp |= __GFP_NOWARN;
+
 	/* Don't support bulk alloc for high-order pages */
 	if (unlikely(pp_order))
 		return page_to_netmem(__page_pool_alloc_page_order(pool, gfp));
-- 
2.51.0