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 9E3191991D4 for ; Wed, 13 May 2026 04:26:14 +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=1778646374; cv=none; b=U81e65tLpkLGFA2AHdIyCnkVR5VU7KebLvQetX43Ta3GZBEchUNG5cG5I6IJGXC6TnPl0i1qsQxvodJezBO78V2MEkAjRx5+tE3xDR/BkgJ6wmz/B9IhQw23VUf1QZ0rqMbvmm5V7UEbLbn/3sp13veBnJxWpO8mCt8lyxQGDtE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778646374; c=relaxed/simple; bh=qBM0+u3s6nJHVR5SgPjCmw32kkJ8ig2nU/GZkZjWql0=; h=Date:To:From:Subject:Message-Id; b=EAj9YYgYCEP3V9W29xftT5tQYQ6NOwXi2Ff0yU8tVhIMANdzt30qF6rm7XGvCC3JnfQ1Q9Ai70/il0mwX4qCCk0XygvLgsTDOKdQt7DRFvQ+c5jKvYw5MM7w9JWUfLibqbe1zjpj7aaKJ3tQrEzFLfU9AVLv7sM5xi3mTpdpNVk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=xVHYv2D/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="xVHYv2D/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10CECC2BCB7; Wed, 13 May 2026 04:26:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1778646374; bh=qBM0+u3s6nJHVR5SgPjCmw32kkJ8ig2nU/GZkZjWql0=; h=Date:To:From:Subject:From; b=xVHYv2D/w+0bB3J6Ck/RTTRKbqMUA90MKG/cO7u+NhlTJcetWgq0KoSSqCjPiI8ZF Ac/Mv3x9GzrkTnDfpCKkwEKlHw3QuQrOgS7c5/jFIbzCQpf5I6TKf3IK5NFzcmREOc 9i8D/i4bvf7paYixeCdE8MsnL3fktzu6RcCCeVgU= Date: Tue, 12 May 2026 21:26:13 -0700 To: mm-commits@vger.kernel.org,osalvador@suse.de,muchun.song@linux.dev,david@kernel.org,ekffu200098@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-hugetlb_cma-restrict-hugetlb_cma-parameter-to-gigantic-page-alignment.patch added to mm-new branch Message-Id: <20260513042614.10CECC2BCB7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/hugetlb_cma: restrict hugetlb_cma parameter to gigantic-page alignment has been added to the -mm mm-new branch. Its filename is mm-hugetlb_cma-restrict-hugetlb_cma-parameter-to-gigantic-page-alignment.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb_cma-restrict-hugetlb_cma-parameter-to-gigantic-page-alignment.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Sang-Heon Jeon Subject: mm/hugetlb_cma: restrict hugetlb_cma parameter to gigantic-page alignment Date: Sun, 3 May 2026 17:42:25 +0900 Existing hugetlb_cma parameter handling logic rejects sizes smaller than one gigantic page, but rounds up larger sizes that are not a multiple of it. The two behaviors are inconsistent and neither is documented. To remove existing inconsistent and undefined behavior, restrict hugetlb_cma parameter to only accept multiples of the gigantic page size. After this restriction, the redundant round_up() in the allocation loop can be removed. The new restriction is also documented in kernel-parameters.txt. Also, including other minor changes for readability improvement with no functional change. Link: https://lore.kernel.org/20260503084225.415980-1-ekffu200098@gmail.com Signed-off-by: Sang-Heon Jeon Suggested-by: Muchun Song Acked-by: Muchun Song Acked-by: Oscar Salvador Cc: David Hildenbrand Signed-off-by: Andrew Morton --- Documentation/admin-guide/kernel-parameters.txt | 4 + mm/hugetlb_cma.c | 35 ++++++-------- 2 files changed, 20 insertions(+), 19 deletions(-) --- a/Documentation/admin-guide/kernel-parameters.txt~mm-hugetlb_cma-restrict-hugetlb_cma-parameter-to-gigantic-page-alignment +++ a/Documentation/admin-guide/kernel-parameters.txt @@ -2100,6 +2100,10 @@ Kernel parameters Format: nn[KMGTPE] or (node format) :nn[KMGTPE][,:nn[KMGTPE]] + The size must be a multiple of the gigantic page size. + When using node format, this applies to each per-node size. + Missaligned values are dropped with a warning. + Reserve a CMA area of given size and allocate gigantic hugepages using the CMA allocator. If enabled, the boot-time allocation of gigantic hugepages is skipped. --- a/mm/hugetlb_cma.c~mm-hugetlb_cma-restrict-hugetlb_cma-parameter-to-gigantic-page-alignment +++ a/mm/hugetlb_cma.c @@ -142,7 +142,7 @@ unsigned int __weak arch_hugetlb_cma_ord void __init hugetlb_cma_reserve(void) { - unsigned long size, reserved, per_node, order; + unsigned long size, reserved, per_node, order, gigantic_page_size; bool node_specific_cma_alloc = false; int nid; @@ -162,37 +162,36 @@ void __init hugetlb_cma_reserve(void) * breaking this assumption. */ VM_WARN_ON(order <= MAX_PAGE_ORDER); + gigantic_page_size = PAGE_SIZE << order; hugetlb_bootmem_set_nodes(); for (nid = 0; nid < MAX_NUMNODES; nid++) { - if (hugetlb_cma_size_in_node[nid] == 0) + size = hugetlb_cma_size_in_node[nid]; + if (size == 0) continue; if (!node_isset(nid, hugetlb_bootmem_nodes)) { pr_warn("hugetlb_cma: invalid node %d specified\n", nid); - hugetlb_cma_size -= hugetlb_cma_size_in_node[nid]; - hugetlb_cma_size_in_node[nid] = 0; - continue; - } - - if (hugetlb_cma_size_in_node[nid] < (PAGE_SIZE << order)) { - pr_warn("hugetlb_cma: cma area of node %d should be at least %lu MiB\n", - nid, (PAGE_SIZE << order) / SZ_1M); - hugetlb_cma_size -= hugetlb_cma_size_in_node[nid]; - hugetlb_cma_size_in_node[nid] = 0; + } else if (!IS_ALIGNED(size, gigantic_page_size)) { + pr_warn("hugetlb_cma: cma area of node %d must be a multiple of %lu MiB\n", + nid, gigantic_page_size / SZ_1M); } else { node_specific_cma_alloc = true; + continue; } + + hugetlb_cma_size -= size; + hugetlb_cma_size_in_node[nid] = 0; } /* Validate the CMA size again in case some invalid nodes specified. */ if (!hugetlb_cma_size) return; - if (hugetlb_cma_size < (PAGE_SIZE << order)) { - pr_warn("hugetlb_cma: cma area should be at least %lu MiB\n", - (PAGE_SIZE << order) / SZ_1M); + if (!IS_ALIGNED(hugetlb_cma_size, gigantic_page_size)) { + pr_warn("hugetlb_cma: cma area must be a multiple of %lu MiB\n", + gigantic_page_size / SZ_1M); hugetlb_cma_size = 0; return; } @@ -204,7 +203,7 @@ void __init hugetlb_cma_reserve(void) */ per_node = DIV_ROUND_UP(hugetlb_cma_size, nodes_weight(hugetlb_bootmem_nodes)); - per_node = round_up(per_node, PAGE_SIZE << order); + per_node = round_up(per_node, gigantic_page_size); pr_info("hugetlb_cma: reserve %lu MiB, up to %lu MiB per node\n", hugetlb_cma_size / SZ_1M, per_node / SZ_1M); } @@ -223,15 +222,13 @@ void __init hugetlb_cma_reserve(void) size = min(per_node, hugetlb_cma_size - reserved); } - size = round_up(size, PAGE_SIZE << order); - snprintf(name, sizeof(name), "hugetlb%d", nid); /* * Note that 'order per bit' is based on smallest size that * may be returned to CMA allocator in the case of * huge page demotion. */ - res = cma_declare_contiguous_multi(size, PAGE_SIZE << order, + res = cma_declare_contiguous_multi(size, gigantic_page_size, HUGETLB_PAGE_ORDER, name, &hugetlb_cma[nid], nid); if (res) { _ Patches currently in -mm which might be from ekffu200098@gmail.com are mm-sparse-remove-unnecessary-null-check-before-allocating-mem_section.patch mm-hugetlb_cma-restrict-hugetlb_cma-parameter-to-gigantic-page-alignment.patch