From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 72B0C3EDE49; Tue, 12 May 2026 17:54:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778608461; cv=none; b=armdKu0YAYcN32/OyL7uu1iLTjJwY36/TxPGxbbwv/yfSq60PheMAjmq84e++VvIqD+1xneM3Nn2NihQxNb8fqADJH+9F4M1a/zACbAo2AtvLw3JpaURBmAiSrl5TLk7Qn/A0jhuZFmPvvk++2sJDmi4L6BIgvxKyBtDYH48ljU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778608461; c=relaxed/simple; bh=W+rxMPl2G3rPPYFg/LG6FL9tbekM4KEMMP+s64JS8XA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XBdpuf7B/5A5nP3FymNk6S2O1WhubsQabnuLIoEAnlgOwHZRnFJg7DfR3bJ92AIKKUZqF0nt3MTNNgm9otP5tAit7wp6QFfukB7rCCYjd0ZU2zdLQsqAxuTMdJeQOvty3IdxlEjsdeY7jPi1IJlzb/HlYP+67vxgBURVu/bzykc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=X65y8gef; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="X65y8gef" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF90AC2BCB0; Tue, 12 May 2026 17:54:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778608461; bh=W+rxMPl2G3rPPYFg/LG6FL9tbekM4KEMMP+s64JS8XA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X65y8gefFP+TKMhoZFgCPbYQGO4BlqLvkVR13eoupXfmVHHMrNVf1DkvGI1lMywqF PcIGmL1KJnXG6ODgWHN2zLfTA7AO2gGEqkhOHs2pkQT3OWf/xjbkdNozm/mBIHsfhU Lh+Lf1Lqlo8ijpP8DNdrEChTX19MnVCU03mBlBuE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sang-Heon Jeon , Muchun Song , David Hildenbrand , Oscar Salvador , Andrew Morton Subject: [PATCH 6.18 089/270] mm/hugetlb_cma: round up per_node before logging it Date: Tue, 12 May 2026 19:38:10 +0200 Message-ID: <20260512173940.334694986@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260512173938.452574370@linuxfoundation.org> References: <20260512173938.452574370@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sang-Heon Jeon commit 8f5ce56b76303c55b78a87af996e2e0f8535f979 upstream. When the user requests a total hugetlb CMA size without per-node specification, hugetlb_cma_reserve() computes per_node from hugetlb_cma_size and the number of nodes that have memory per_node = DIV_ROUND_UP(hugetlb_cma_size, nodes_weight(hugetlb_bootmem_nodes)); The reservation loop later computes size = round_up(min(per_node, hugetlb_cma_size - reserved), PAGE_SIZE << order); So the actually reserved per_node size is multiple of (PAGE_SIZE << order), but the logged per_node is not rounded up, so it may be smaller than the actual reserved size. For example, as the existing comment describes, if a 3 GB area is requested on a machine with 4 NUMA nodes that have memory, 1 GB is allocated on the first three nodes, but the printed log is hugetlb_cma: reserve 3072 MiB, up to 768 MiB per node Round per_node up to (PAGE_SIZE << order) before logging so that the printed log always matches the actual reserved size. No functional change to the actual reservation size, as the following case analysis shows 1. remaining (hugetlb_cma_size - reserved) >= rounded per_node - AS-IS: min() picks unrounded per_node; round_up() returns rounded per_node - TO-BE: min() picks rounded per_node; round_up() returns rounded per_node (no-op) 2. remaining < unrounded per_node - AS-IS: min() picks remaining; round_up() returns round_up(remaining) - TO-BE: min() picks remaining; round_up() returns round_up(remaining) 3. unrounded per_node <= remaining < rounded per_node - AS-IS: min() picks unrounded per_node; round_up() returns rounded per_node - TO-BE: min() picks remaining; round_up() returns round_up(remaining) equals rounded per_node Link: https://lore.kernel.org/20260422143353.852257-1-ekffu200098@gmail.com Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma") # 5.7 Signed-off-by: Sang-Heon Jeon Reviewed-by: Muchun Song Cc: David Hildenbrand Cc: Oscar Salvador Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/hugetlb_cma.c | 1 + 1 file changed, 1 insertion(+) --- a/mm/hugetlb_cma.c +++ b/mm/hugetlb_cma.c @@ -193,6 +193,7 @@ void __init hugetlb_cma_reserve(int orde */ per_node = DIV_ROUND_UP(hugetlb_cma_size, nodes_weight(hugetlb_bootmem_nodes)); + per_node = round_up(per_node, PAGE_SIZE << order); pr_info("hugetlb_cma: reserve %lu MiB, up to %lu MiB per node\n", hugetlb_cma_size / SZ_1M, per_node / SZ_1M); }