From nobody Sun Feb 8 11:59:32 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A8BC03126A3 for ; Mon, 12 Jan 2026 15:46:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768232811; cv=none; b=ngvOpyNvVc2wc/0uDq8wyhiespY25sxhijmaXPBX6+jL+nb6kdPGuenirrx5SHTIkAhbt30rPAZAHo5ICooi1CSZ2LdEwrWxhph9xu0cLpu+pRik9Uab4zVyVk4n+EQkyv5wW1oDsWJ7DQJ0AthQDWmxyAZv4cPmPiLfQiOUtqk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768232811; c=relaxed/simple; bh=th2YzedDg+I+Z++h/5UVgR6l3o0jgXTasXPuIBPLus0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=SWTAOTG1DU1A23vZHFvbknUZtK5qOnDLO8QpgdMjhQjv6zLz1+mApehidH6otp1v5Wmq/wpffV4s8CTpjEyjfPg4eXisntFpr0H3BXgnqLKZ/0EIGRNqeOL8YwkRSU7d4D7z3siamX8Yh9rL+zl1WZ0uvSWNTEiVAtqo4igmVK8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 43C981516; Mon, 12 Jan 2026 07:46:42 -0800 (PST) Received: from 010265703453.arm.com (unknown [10.57.48.115]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8CA563F694; Mon, 12 Jan 2026 07:46:46 -0800 (PST) From: Robin Murphy To: m.szyprowski@samsung.com, akpm@linux-foundation.org, vbabka@suse.cz, david@kernel.org Cc: bhe@redhat.com, iommu@lists.linux-foundation.org, linux-mm@kvack.org, vladimir.kondratiev@mobileye.com, s-adivi@ti.com, linux-kernel@vger.kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com Subject: [PATCH 1/3] dma/pool: Improve pool lookup Date: Mon, 12 Jan 2026 15:46:36 +0000 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" If CONFIG_ZONE_DMA32 is enabled, but we have not allocated the corresponding atomic_pool_dma32, dma_guess_pool() may return the NULL value of that and fail a GFP_DMA32 allocation without trying to fall back to other pools which may exist. Furthermore, if no GFP_DMA pool exists, it is preferable to try GFP_DMA32 rather than immediately fall back to GFP_KERNEL with even less chance of success. Improve matters by encoding an explicit order of pool preference for each flag. Signed-off-by: Robin Murphy --- kernel/dma/pool.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 26392badc36b..2645cfb5718b 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -224,10 +224,10 @@ postcore_initcall(dma_atomic_pool_init); static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t= gfp) { if (prev =3D=3D NULL) { - if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32)) - return atomic_pool_dma32; - if (atomic_pool_dma && (gfp & GFP_DMA)) - return atomic_pool_dma; + if (gfp & GFP_DMA) + return atomic_pool_dma ?: atomic_pool_dma32 ?: atomic_pool_kernel; + if (gfp & GFP_DMA32) + return atomic_pool_dma32 ?: atomic_pool_dma ?: atomic_pool_kernel; return atomic_pool_kernel; } if (prev =3D=3D atomic_pool_kernel) --=20 2.34.1