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AFNElJ/T12wGGkweFxtoHB4QyxFcHg1gCD0jeZJcnH8t2ZYEFsBrT6330kywI2Aehmx9nVJA0/Ur8AgE1Q==@kvack.org X-Gm-Message-State: AOJu0Yxzb0rEj+hQ+l/RncpDowMy2IkkU6iodIYH0RG81IESvDq0vqsB 1pfE+JMsPtXyePbhWax/S3mBl6dRmIWV4EHIQuhhcO515h3xOtPQre0JxF5FiY4p5KxixS9Vyh4 vw3IevTCc4Bo3SWy0Ee39tDLvfw== X-Received: from pfwz36.prod.google.com ([2002:a05:6a00:1da4:b0:845:aa6d:92ea]) (user=souravpanda job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2989:b0:842:708f:39a0 with SMTP id d2e1a72fcca58-845b39e15ecmr4983540b3a.8.1782424742033; Thu, 25 Jun 2026 14:59:02 -0700 (PDT) Date: Thu, 25 Jun 2026 21:59:00 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.rc0.799.gd6f94ed593-goog Message-ID: <20260625215900.2151690-1-souravpanda@google.com> Subject: [PATCH v1] mm/hugetlb_cma: support percentage-based hugetlb_cma reservation From: Sourav Panda To: muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org Cc: david@kernel.org, surenb@google.com, fvdl@google.com, gthelen@google.com, souravpanda@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 934544000B X-Rspam-User: X-Stat-Signature: zx33a7bcybq45fqoobffm593sdmcyzjk X-HE-Tag: 1782424743-145384 X-HE-Meta: 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 N93u4Fba 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Currently, hugetlb_cma reservation only supports absolute sizes (e.g., hugetlb_cma=2G or hugetlb_cma=0:1G,1:1G). This can be restrictive in heterogeneous environments or when deploying common kernel command lines across machines with different memory capacities. Add support for percentage-based hugetlb_cma reservation (e.g., hugetlb_cma=20% or hugetlb_cma=0:20%,1:10%). The percentage is calculated against the total memory (for global settings) or against the node-specific memory (for node-specific settings) using memblock APIs during early boot. Signed-off-by: Sourav Panda --- .../admin-guide/kernel-parameters.txt | 7 +- mm/hugetlb_cma.c | 81 ++++++++++++++++++- 2 files changed, 82 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5a05b48d1684..846940ce2858 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2064,8 +2064,11 @@ Kernel parameters hugetlb_cma= [HW,CMA,EARLY] The size of a CMA area used for allocation of gigantic hugepages. Or using node format, the size of a CMA area per node can be specified. - Format: nn[KMGTPE] or (node format) - :nn[KMGTPE][,:nn[KMGTPE]] + The size can be an absolute value (e.g., 2G) or a + percentage of the total memory or node memory (e.g., 20%). + Format: nn[KMGTPE] or nn% or (node format) + :nn[KMGTPE][,:nn[KMGTPE]] or + :nn%[,:nn%] Reserve a CMA area of given size and allocate gigantic hugepages using the CMA allocator. If enabled, the diff --git a/mm/hugetlb_cma.c b/mm/hugetlb_cma.c index 7693ccefd0c6..b4f8bbe4c62d 100644 --- a/mm/hugetlb_cma.c +++ b/mm/hugetlb_cma.c @@ -9,6 +9,8 @@ #include #include +#include +#include #include "internal.h" #include "hugetlb_cma.h" @@ -18,6 +20,28 @@ static unsigned long hugetlb_cma_size_in_node[MAX_NUMNODES] __initdata; static bool hugetlb_cma_only __ro_after_init; static unsigned long hugetlb_cma_size __ro_after_init; +static unsigned int hugetlb_cma_percent __initdata; +static unsigned int hugetlb_cma_percent_in_node[MAX_NUMNODES] __initdata; + +#ifdef CONFIG_NUMA +static unsigned long __init memblock_node_memory_size(int nid) +{ + struct memblock_region *reg; + unsigned long size = 0; + + for_each_mem_region(reg) { + if (reg->nid == nid) + size += reg->size; + } + return size; +} +#else +static unsigned long __init memblock_node_memory_size(int nid) +{ + return memblock_phys_mem_size(); +} +#endif + void hugetlb_cma_free_frozen_folio(struct folio *folio) { WARN_ON_ONCE(!cma_release_frozen(hugetlb_cma[folio_nid(folio)], @@ -100,14 +124,27 @@ static int __init cmdline_parse_hugetlb_cma(char *p) break; if (s[count] == ':') { + char *next; + if (tmp >= MAX_NUMNODES) break; nid = array_index_nospec(tmp, MAX_NUMNODES); s += count + 1; - tmp = memparse(s, &s); - hugetlb_cma_size_in_node[nid] = tmp; - hugetlb_cma_size += tmp; + tmp = memparse(s, &next); + if (*next == '%') { + if (tmp > 100) { + pr_warn("hugetlb_cma: invalid percentage %lu for node %d\n", + tmp, nid); + break; + } + hugetlb_cma_percent_in_node[nid] = tmp; + s = next + 1; + } else { + hugetlb_cma_size_in_node[nid] = tmp; + hugetlb_cma_size += tmp; + s = next; + } /* * Skip the separator if have one, otherwise @@ -118,7 +155,17 @@ static int __init cmdline_parse_hugetlb_cma(char *p) else break; } else { - hugetlb_cma_size = memparse(p, &p); + char *next; + + tmp = memparse(p, &next); + if (*next == '%') { + if (tmp > 100) + pr_warn("hugetlb_cma: invalid percentage %lu\n", tmp); + else + hugetlb_cma_percent = tmp; + } else { + hugetlb_cma_size = tmp; + } break; } } @@ -144,8 +191,34 @@ void __init hugetlb_cma_reserve(void) { unsigned long size, reserved, per_node, order; bool node_specific_cma_alloc = false; + bool has_node_specific_param = false; int nid; + for (nid = 0; nid < MAX_NUMNODES; nid++) { + if (hugetlb_cma_size_in_node[nid] || hugetlb_cma_percent_in_node[nid]) { + has_node_specific_param = true; + break; + } + } + + if (has_node_specific_param) { + for (nid = 0; nid < MAX_NUMNODES; nid++) { + if (hugetlb_cma_percent_in_node[nid]) { + unsigned long node_gfp_mem = memblock_node_memory_size(nid); + unsigned long s; + + s = mult_frac(node_gfp_mem, + hugetlb_cma_percent_in_node[nid], + 100); + + hugetlb_cma_size_in_node[nid] = s; + hugetlb_cma_size += s; + } + } + } else if (hugetlb_cma_percent) { + hugetlb_cma_size = mult_frac(memblock_phys_mem_size(), hugetlb_cma_percent, 100); + } + if (!hugetlb_cma_size) return; -- 2.55.0.rc0.799.gd6f94ed593-goog